Hongsuan for “Sour Soup” Fish, Beef, Hotpot and More

Though rarely encountered in the United States, Guizhou’s Hot and Sour Tomato Hotpot (酸汤火锅, suāntāng huǒguō) is a wonderful broth variation to add to your repertoire.  

Usually, if I’m hosting a hotpot party, a good mala broth base is a must. Sichuan people may have invented the mala flavor profile, but it swept China and then the rest of the world simply because it’s addictive. In Sichuan and Chongqing, the locals eat their fiery hotpot well into summer, when your sweat glands go into overdrive even as your face is melting from heat and capsaicin. This counterintuitively cools the body, so that by the end of the meal, one gets up from the table dewy, refreshed, reborn.

But lately, as winter deepens, I’ve been craving cozy umami flavors, with just enough spice to warm the bones and just enough acid to ward off sluggishness. In these moments, a mala hotpot thick with beef tallow can just be… too much.

These highly specific urges led me to Guizhou-style hot and sour broths, made with both fermented tomatoes and fermented chilies.

In Guizhou, which sits cradled between Sichuan, Hunan, Guangxi and Yunnan, these ferments—as well as the broths for which they serve as the base—are known as 酸汤 (suāntāng), sour soup. They are part of the Miao culinary repertoire.

Amongst the Miao people, there is a rhyming idiom: 三天不吃酸，走路打窜窜 (sān tiān bù chī suān, zǒulù dǎ cuàncuàn)—“Three days without eating sour will have one walking in circles.” Aside from lacto-fermentation being a key preservation technique within the climate (subtropical) and ecology (lush) of Guizhou, this saying suggests a deeper connection to acid: that it’s essential for maintaining basic health and vigor.

Of course, modern nutrition science has since proven the Miao people right: Lacto-fermented foods are in fact great for you!

[Sidenote: For a tidy intro on Miao food culture in Guizhou, I highly recommend this clip, produced by the Guizhou Tourism Board and bearing English subtitles, which features the famous Lianghuanzhai Sour Soup Fish restaurant in Kaili. I especially like the part, about five minutes in, when the owner talks about suantang being the secret to her youthful good looks.]

So What Is Suantang?

The Miao use a dazzling array of ferments in their cooking. Within the category of suantang, there is, most simplistically, 白酸汤 (bái suāntāng), white sour soup, and 红酸汤 (hóng suāntāng), red sour soup. The white version, baisuan for short, is made by simply letting the starchy water made from boiling rice go sour over the course of a few days. Hongsuan, on the other hand, can be tomatoes and chilies fermented together, or tomatoes and chilies fermented separately (the latter becoming Guizhou’s chili sauce, 糟辣椒 (zāolàjiāo)) and then blended together when cooking.

From hongsuan comes some of Guizhou’s most famous dishes, such as 酸汤鱼 (suāntāngyú), Sour Soup Fish, and 酸汤肥牛 (suāntāng féiniú), Sour Soup Beef, and more recently, 酸汤火锅 (suāntāng huǒguō), a sour and spicy tomato hotpot.

All these dishes use the same broth base, and the methods in the preparation of hongsuan broth vary endlessly: some cooks mix baisuan and blended ferments of chilies and tomatoes, others mix fermented chilies with fresh raw tomatoes, others still use fermented tomatoes AND raw tomatoes. You get the idea. 

My recipe, which starts with fermenting tomatoes and chilies together with garlic and ginger, is an adaptation. It’s meant to keep things as simple as possible while achieving our objective: a punchy, piquant broth that kisses any ingredient you put into it with the perfect balance of savory, spicy and sour.

In Chinese, the phrase 开胃 (kāiwèi), literally “stomach opening,” refers to any dish that really whets the appetite. This broth is the epitome of 开胃.

As I’ve already hinted, you can use this broth for tomato hotpot, but you can also use it to poach whole fish or slices of fish to make Sour Soup Fish, fatty beef slices to make Guizhou-style Sour Soup Beef, or simply as a noodle soup broth. Unlike mala broth, it’s gentle enough to be sipped or spooned over rice. 

Selecting Tomatoes and Chilies

In Guizhou, the tomato used for hongsuan is a flavorful local type of cherry tomato. Wherever you are, try to find analogues—the qualities we’re looking for are snappy red skins, low water content, and FLAVOR.

In other words, stay away from beefsteaks.

However, because so much flavor comes from the fermentation process itself, you also don’t need to waste expensive heirloom tomatoes on this recipe. Some combination of good supermarket varietals such as Roma, cherry, grape or Campari tomatoes would all be fine. 

The chili pepper used in Guizhou, chili pepper capital of China, is most often 红线椒 (hóngxiànjiāo), red thread chilies, which Chinese Cooking Demystified describes as tasting like a cross between erjingtiao and kashmiri chilies, meaning that they are moderately spicy and have concentrated color. They recommend kashmiri chilies for color and cayenne chilies for heat.

For folks with access to an Asian supermarket, bird’s eye chilies, which grow slightly further south in Yunnan and Guangxi, are also a good substitute, and it’s what I use here. Bird’s eye is smaller and spicier than thread chili, however, so I’ve decreased the quantity accordingly.

Fermentation Tips for Tomato Hotpot Base

Like Sichuan paocai (as well as sauerkraut, dill pickles, kimchi and many other famous ferments) suantang is essentially a lacto-ferment: Ingredients are “pickled” using salt, which inhibits the growth of spoilage bacteria and allows for the growth of Lactobacillus bacteria. Lactobacillus converts sugars into lactic acid, thus creating those complex, tangy flavors enjoyed by people the world over. 

Lacto-fermentation may be one of the oldest preservation techniques in the world, and thus also one of the simplest. The only real requirement is adding enough salt to inhibit spoilage—a minimum of 2% and maximum of 5% by weight of the combined organic matter you are fermenting. At 2%, fermentation happens more rapidly; at 5%, it takes longer.

Temperature also plays a role—a spot next to the heater set at 75°F will yield faster fermentation than a cool 60°F pantry. Observation is key—more than this recipe, your eyes and nose will tell you when the suantang is ready.

Aside from staying within this zone, there is a lot of room to play (The Noma Guide to Fermentation uses 456 pages to do exactly that). The proportions of tomato to chilies, as well as the amounts of garlic and ginger, are all adjustable. A Guizhou palate may well want to use the higher end of the chili quantity I’ve included, or go even higher, while my Nanjing tastebuds are quite happy at the lower end. 

Once the suantang is done fermenting, you can decant the mixture into glass jars for long-term fridge storage.

If you encounter surface mold during fermentation (not to be confused with harmless kahm yeast), it is safest to throw the batch away and start over. Personally, I did not have a big problem with mold, more so with kahm yeast.