Hainan Zao Po Vinegar & Fuzhou Hujiu: The Two Sour Broths of China's Southern Coast

Most British eaters meet Chinese sour flavours through two doors. The first is Sichuan, where sourness arrives disguised as numbing heat; the second is Guizhou, where a tomato-and-fermented-chilli base does the talking. Both are wonderful and both have been written about endlessly. Lost in the noise is a third tradition, quieter and older, running along China's southern coast from the Leizhou Peninsula across the strait to Hainan Island, then back up to the Fujian capital of Fuzhou. These are the coastal sour broths, and they work on a different logic. Where landlocked sour soups lean on vegetables and wild herbs, the southern coast leans on the by-products of rice wine. Sourness here is not a seasoning added at the table. It is something that happens inside a jar, over weeks, while nobody is watching.

A Sichuan base announces itself. A coastal sour broth arrives looking modest — a pale milky liquid or a clear amber one — and then widens in the mouth in a way that is hard to place if you have only ever tasted vinegar from a bottle. Two of these broths are far easier to find in Britain than they were a few years ago, and the difference between them is worth understanding before you buy hot pot base in the UK and discover, halfway through a meal, that you have chosen something quite unlike what you expected.

The two broths are Hainan zao po vinegar, zao po cu, and Fuzhou hujiu broth, hujiu zhi. One is bright, tangy and built for shellfish. The other is savoury, deep and built for pork and offal as much as for fish. They share a coastline, a dependence on fermented rice, and almost nothing else.

What Zao Po Actually Means: The Second Life of Rice Wine

The Chinese term zao po is usually translated as "dregs" or "lees", which in English sounds like rubbish. In the Chinese food economy it means almost the opposite. When rice is fermented to make wine or distilled spirit, what remains after the liquid is drawn off is a dense, fragrant mass of grain, yeast and residual sugars. That mass is zao. Across southern China it is not thrown away. It is eaten, used to cure fish and pork, folded into sauces, and in some places buried in jars to ferment further into something entirely new. The logic is practical: a rice harvest is hard work, fermentation is slow work, and nothing that still carries flavour should go into the river.

In Hainan that thrift became a specific product. Households and small workshops around Wenchang, on the island's north-eastern coast, combine the lees left from local rice wine and rice spirits with rice vinegar, fresh chilli, garlic and salt, then leave the mixture to work. The lees carry living yeast and residual starch; the vinegar brings acidity; the chilli and garlic contribute aroma and antimicrobial bite. Over days and weeks it settles into a cloudy, pale-golden liquid that smells sharp, yeasty and faintly sweet — closer in spirit to a young kombucha or a wild ale than to the cleaning-cupboard vinegar most British kitchens keep.

This is why the name confuses people. Zao po cu reads like "dregs vinegar", and the image it conjures is the opposite of what it tastes like. Locals will tell you the flavour is clean. Drink a spoonful neat and you get a forward tang, then a soft roundness from the grain, then a low warmth from the chilli that arrives late and never dominates. It is sour without being austere, achieved because the sourness comes from two sources at once: the sharp volatile acidity of vinegar, and the gentler lactic and organic acids produced by the grain fermenting in the jar.

The Story From Puqian, Told As A Local Saying

Ask where zao po vinegar comes from and you will most often be pointed to Puqian, an old port town in Wenchang on Hainan's north coast, facing the Qiongzhou Strait. The most repeated origin story is folk history rather than documented record, and it is usually offered that way — as a local saying, a tale told at the table rather than an entry in a chronicle. In the common telling, a family near Puqian kept a jar of rice wine lees they could not bear to discard, added vinegar and aromatics to stretch it, and found some time later that the jar had turned into a fragrant sour broth. Neighbours copied it, fishermen took it out on the water, and within a generation it had stopped being an accident and become a recipe.

Why Hainan Zao Po Vinegar Was Born To Meet Seafood

Hainan cooks do not treat zao po vinegar as an all-purpose condiment. They pair it, with remarkable consistency, with the sea. The reason is technical before it is cultural. Fish and shellfish carry amines that read as fishiness when they concentrate, and those compounds are volatile and alkaline. Acid neutralises them and drives them off. A squeeze of lemon does this; a broth of fermented rice vinegar does it more thoroughly, because the acid is present in quantity and the aromatics of chilli and garlic work alongside it. A strong-tasting fish, or a prawn that has sat in a market a few hours too long, comes out of a zao po bath tasting sweet and clean.

The pairing goes further than deodorising. Coastal sour broths are usually built on a stock made with fish bones, shellfish shells or a light meat broth, and the sourness sharpens that base rather than fighting it. In practice a Hainan seafood hot pot is assembled in a particular order: shellfish go in first and are eaten the moment they open, then prawns, then firm white fish, then vegetables that have soaked up the sourness. Noodles go in last, into a broth that has absorbed everything the sea has given up. This uses the broth as a tool rather than a backdrop, and it works because the broth stays sharp from the first shell to the last noodle.

There is a social dimension too. In Wenchang and along the northern Hainan coast, sour seafood hot pot is a gathering food rather than a restaurant performance. The broth is made in quantity in a family kitchen, the table is loaded with whatever came off the boat that morning, and the meal lasts for hours. Visitors to Hainan often describe the local hot pot as the best thing they ate on the island, and almost always say the same thing about it: it tastes like the sea, but brighter. That brightness is fermented rice, doing quiet work in a pot.

Fuzhou Hujiu: The Other Sour, And Why "Hujiu" Means Fuzhou

Move north-east along the coast to Fuzhou, capital of Fujian province, and the same raw material takes a different form and a very different flavour direction. The word hujiu on a menu or a package is not an ingredient name. It is Fuzhou dialect. In the local Min language the city's name is pronounced something close to "Hujiu", and that pronunciation has been carried onto labels and shop signs, so a hujiu hot pot base is simply a Fuzhou-style base, named in the speech of the people who invented it. The otherwise opaque term becomes a useful signpost: what follows will be Fuzhou food, and Fuzhou food follows its own rules.

Fujian cuisine is famous across China for its red wine lees, hong zao, the deep-red by-product of brewing local rice wine, used to marinade, braise and fry everything from pork to crab. It gives Fuzhou cooking its characteristic colour and savoury depth — lightly alcoholic, faintly sweet, intensely umami, and almost never spicy. Fuzhou is not a chilli-eating city in the way Chengdu or Changsha are. Its sourness, where it appears, comes from fermentation and preserved ingredients rather than fresh heat, and its broths are built to taste rounded and rich rather than aggressive.

Hujiu broth fits that description exactly. It is a savoury, amber-toned base, in most versions clear rather than cloudy, with the sour note sitting beside a pronounced savoury-sweet character from the fermented rice. Many versions lean on seafood and pork together — dried scallop, prawn, anchovy, sometimes a little pork bone — giving the broth a depth a purely vegetarian sour base cannot reach. The first impression is usually not "sour" at all. It is "rich". The acidity appears underneath, holding the richness in check, and the whole thing is balanced around a fermented-rice core closer to a good fish sauce or a mature miso than to anything in a vinegar bottle.

A Direct Comparison Between The Two Broths

Set the two side by side and the differences are easy to describe. Hainan zao po vinegar is a hot-country sour: cloudy and pale gold, sometimes with visible sediment from the rice lees, tangy on the front of the tongue, with chilli and garlic carrying through the aroma. Fuzhou hujiu is a temperate-coast sour: clean and amber, savoury-sweet from fermented rice, restrained on chilli or entirely without it, deeper and longer on the finish. The Hainan bottle is the one you reach for with prawns, clams, crab and squid. The Fuzhou bottle is the one you reach for with pork belly, beef, fish balls, tofu and greens, or with shellfish when you want savoury to lead rather than tang.

Their ideal guest lists differ for the same reason. Zao po vinegar wants food with a clean, saline, mineral character so its acidity has something to cut. Hujiu wants food with fat and collagen, because its savoury depth has somewhere to go when it meets richness. Serve a delicate oyster in a heavy hujiu broth and the broth wins; serve a slab of pork belly in a bright zao po broth and the broth is overwhelmed from the other direction. None of this is a rule written down in Fujian or Hainan. It is what decades of everyday cooking has settled on.

Fermented Sourness In A British Frame Of Reference

British and European cooks already understand this kind of acidity. They simply call it something else. Sourdough is the clearest example: a leavened bread whose tang comes from lactic and acetic acids produced by wild fermentation of grain, and which would be bland without them. Kimchi turns cabbage sharp, fizzy and complex. Fish sauce is what happens when salt and time convert fish protein into a liquid that tastes of savoury depth rather than of fish. Blue cheese rests entirely on controlled acidity and controlled decay. None of these are strange to a British palate. A Hainan sour broth is in the same family, built on rice rather than wheat, cabbage or fish.

The practical consequence is that the vocabulary of a British kitchen is already adequate for describing zao po vinegar. If you like the acidity of a good sourdough, or the tang of a dry cider next to roast pork, you already have the taste reference. The flavour of a coastal sour hot pot is not "Chinese food" in the generic sense a British diner might expect from a takeaway menu. There is no sweet-and-sour sauce, no thick batter, no neon orange. It is a broth with the logic of a bowl of pot-au-feu served with cornichons: acid placed deliberately against richness to keep a heavy meal drinkable. Britain has its own history of using fermentation to stretch a harvest and keep protein edible through the winter, and southern Chinese coastal fermentation is the same instinct operating in a hotter climate, where the enemy is not winter but heat.

How To Eat It At Home: Dilution, Dipping And The Order Of Cooking

Both broth families arrive as a concentrated soup base, not a ready-to-drink stock, and treating them as stock is the single most common mistake. A typical ratio is somewhere between one part base to three and one part to five parts water, though the exact figure varies by brand and by how assertive you want the finished broth. Start weaker than you think you need. Over-diluted fermented broth tastes flat; too strong and it becomes bracing and one-note. You can always add more base halfway through a meal, once the ingredients have started giving their own flavour to the pot.

Bring the diluted broth to a gentle simmer rather than a rolling boil. Fermented rice broths are aromatic and volatile, and a hard boil drives off exactly the fragrance you bought them for. A wide shallow pot — an electric hot pot, a portable induction hob with a pan, or a fondue set on the kitchen table — works better than a deep stockpot, because everything cooks fast and everyone can reach it. Dried ingredients such as mushrooms, dried scallop or kombu benefit from going in first and steeping for ten minutes before anyone eats.

What To Cook In It, And How To Build The Dipping Bowl

For a Hainan-style sour broth, build around the sea. Raw peeled prawns take under a minute a side. Mussels and clams should be cooked just until they open and then removed, so they do not toughen. Firm white fish cut into thick slices, squid scored and cut into pieces, and scallops all hold up, and scallops take on a beautiful sweetness from the acid. Add enoki or shiitake mushrooms, wedges of white cabbage, thin slices of daikon and a few stems of pak choi, then finish with wheat noodles or thin rice noodles in the last two minutes so they pick up everything the seafood has released.

For a Fuzhou-style hujiu broth, build around fat and savoury. Thin-sliced beef, pork belly cut paper-thin, pork meatballs, fish balls, firm tofu and fried tofu skin all work, along with clams for a lift of brine. Leafy greens, Chinese cabbage, lotus root, potato slices and corn segments give the pot body. Many Fuzhou hot pots finish with a small bowl of rice or a few noodles to mop up the now heavily flavoured broth. Either broth can be drunk at the end of the meal, ladled into a small bowl and sipped as it is, or with chopped coriander and a squeeze of lime.

A dipping sauce is not optional in either tradition, but it should not hide the broth. For a Hainan sour broth, keep it light: light soy, a little of the same sour broth, fresh chilli, garlic, a pinch of sugar and plenty of coriander, with a few drops of toasted sesame oil for aroma. For a Fuzhou hujiu broth, lean savoury: light soy with a spoonful of the broth, chopped spring onion, a little ginger, a touch of rice vinegar only if the broth itself is not sour enough, and a shake of white pepper. Both benefit from a small dish of chilli oil on the side, so that the table controls the spice level rather than the pot.

Cooking These Broths In A British Kitchen

The ingredients problem is smaller than it looks. Almost everything that goes into a coastal Chinese sour hot pot has a British supermarket equivalent. Raw king prawns, mussels and clams are in most large supermarket fish counters, and frozen shellfish is available year-round. Firm white fish such as cod and pollock has exactly the right texture for a sour broth. Pork belly, beef shin sliced thin at the butcher's counter, block tofu, daikon, pak choi, shiitake and enoki mushrooms, spring onions, coriander and limes are all mainstream. Chinese cabbage, lotus root and frozen fish balls are worth a trip to an Asian grocer, but they are not essential for a first attempt.

What is genuinely difficult in Britain is the broth itself. These are small regional products with limited distribution, and the versions sold outside China are often poor. This is where sourcing matters more than technique. A well-made Hainan zao po base should smell yeasty, sharp and slightly sweet when you open the jar, and should look cloudy rather than artificially clear. A well-made Fuzhou hujiu base should look like dark amber tea and smell of fermented rice and dried seafood. If a jar smells only of vinegar or only of chilli, that is a sign of a shortcut in production. Anyone searching for where to buy hot pot base in the UK who wants the coastal southern styles rather than the more widely distributed Sichuan ones will find the choice narrower than they expect, so it pays to go to a specialist.

Mixdiff stocks the two coastal families described here. The Hainan zao po vinegar hot pot soup base, a tangy fermented Hainan-style base, comes as a 250g pack from around £8.99, alongside a 150g two-pack and five-pack format at £6.99 and £14.99, and a 1kg catering-size version at £18.99 that suits a large table or a household that cooks hot pot often. The Fuzhou hujiu hot pot soup base, the Fuzhou-style savoury broth, covers the northern Fujian tradition. A 250g pack of concentrated base will comfortably serve three to four people at a generous dilution, so the cost per head is modest compared with eating the same meal out.

Practical Notes Before You Order

Both broths are shelf-stable concentrated bases. Store them in a cool dark cupboard before opening and in the fridge afterwards; a thin film of sediment in a zao po jar is normal and is the rice lees doing their job, not a fault. Once diluted, the broth does not keep well and should be eaten the same day. If you are cooking for one or two, buy a smaller format and dilute it more sparingly. If you are cooking for six or more, the larger format is significantly better value. One thing worth saying plainly to anyone weighing up where to buy hot pot base in the UK for the first time: these broths are not interchangeable with the Sichuan bases most British shoppers know. Do not expect mala heat or a heavy layer of chilli oil. Expect something subtler, with acidity that comes out slowly as the meal goes on and a broth worth drinking at the end.

Frequently Asked Questions

Is zao po vinegar the same as rice vinegar?

No. Rice vinegar is a clear liquid used as a seasoning. Zao po vinegar is a fermented preparation built on rice wine lees, rice vinegar, chilli and garlic, eaten as a broth as often as used as a condiment. Substituting plain rice vinegar gives you acidity but none of the yeasty depth or drinkability of the real thing.

Is hujiu hot and spicy?

Usually not. Fuzhou cooking is not built around chilli heat, and hujiu broth is a savoury, savoury-sweet fermented rice base with a sour edge rather than a spicy one. Some commercial versions add a little chilli, so check the label if you want to keep heat out of the pot. If you want spice, add chilli oil to the dipping bowl rather than the broth.

Can I drink the broth at the end?

Yes, and in both traditions that is largely the point. Ladle the reduced, flavoured broth into small bowls and sip it. It will be saltier and richer at the end of a meal than at the start. If it becomes too intense, top up with a little hot water before drinking.

Do these bases work outside hot pot?

They do, and they are useful in a British kitchen well beyond the hot pot table. Diluted more heavily, either broth makes a good poaching liquid for fish or a base for a noodle soup. A spoonful of Hainan zao po vinegar stirred through a seafood stew, or a splash of hujiu broth added to a braise, brings the same acid-against-richness effect to everyday cooking.

How does mixdiff deliver to Britain?

Products are shipped directly from China to the UK by air, with a typical transit time of eight to twelve calendar days. UK shipping is free on orders over £59. Because these bases are concentrated and shelf-stable, the journey is straightforward, and ordering several jars at once is the sensible way to shop.

The coastal sour broths of Hainan and Fuzhou have survived for a simple reason. They were invented by people who could not afford to waste a harvest, and who made something worth eating out of what was left over. That is a very old kind of cooking, and it is not confined to China — it is the same instinct that gave Britain sourdough, pickles and preserved lemons. For a British cook looking to broaden a hot pot repertoire beyond chilli heat, these two broths are the most rewarding place to start. Find the right jars, dilute them carefully, cook gently, and drink the broth at the end.