Hot and sour soup

Name: Hot and sour soup
Prep time: 20 min
Cook time: 20 min
Total time: 55 min
Cuisine: Chinese
Ingredients: 6 g dried wood ear mushrooms (a crunchy black fungus); 4 dried shiitake mushrooms (about 15 g); 250 ml hot water, for the shiitake; Warm water, for the wood ear; 150 g pork shoulder, cut into thin matchsticks; 1 tsp light soy sauce; 1 tsp Shaoxing wine (Chinese rice wine); 1 tsp cornstarch; 1.2 l chicken stock, unsalted or low-salt; 100 g tinned bamboo shoots, rinsed; 200 g firm tofu; 2 tbsp light soy sauce; 1 tsp dark soy sauce; ½ tsp sugar; ½–1 tsp salt (less if your stock is salted); 3 tbsp cornstarch; 5 tbsp cold water; 2 eggs; 4–6 tbsp Chinkiang black vinegar; 1–2 tsp ground white pepper; 1 tsp sesame oil; 2 spring onions, finely sliced; Chilli oil, to serve (optional)

A thick, glossy chicken broth with pork, mushrooms, bamboo, tofu and egg ribbons, sharp with black vinegar and hot with white pepper. Ready in under an hour.

By the Soupmap Culinary Team

Prep: 20 min
Cook: 20 min
Total: 55 min
Effort: Easy
Serves: 4

The total includes 15 min of soaking, resting or chilling.

Broth richness 4/10

Spice 6/10

Comfort 7/10

Ratings by the Soupmap Culinary Team, not readers.

Dairy-free

Photo: jeffreyw, CC BY 2.0, via Wikimedia Commons

Hot and sour soup, suan la tang ("sour-spicy soup"), is made across northern China and in Sichuan, and at its best it is a jolt: thick and glossy, crowded with fine shreds of pork, mushroom, bamboo shoot and tofu, and both sharp and fiery. The surprise for many people is where the fire comes from. In this style the "hot" is white pepper, and plenty of it, not chilli. It catches at the back of your throat rather than on your lips, and it is what makes the soup so warming.

The sour comes from Chinkiang black vinegar, a dark, malty vinegar from the city of Zhenjiang in eastern China, brewed from glutinous rice. It has a round, almost smoky flavour that plain vinegar can't match.

What usually goes wrong is timing. Vinegar and pepper both lose their edge if they boil, so they go in at the very end, off the heat. And the soup must be thickened before the egg goes in: a thickened broth holds the egg in fine, floating ribbons instead of letting it sink into rubbery clumps.

Method

Prepare

Put the wood ear in a bowl of warm water and the shiitake in the 250 ml hot water. Soak for 30 minutes, until both are completely soft and floppy.
Meanwhile, toss the pork with 1 tsp light soy sauce, the Shaoxing wine and 1 tsp cornstarch and set aside. Cut the bamboo shoots and tofu into matchsticks about the same size as the pork. Beat the eggs in a jug.
Lift out the shiitake and squeeze them over their bowl, then pour the soaking liquid into a jug, leaving any grit behind. Cut off the stems and slice the caps thinly. Drain the wood ear, trim off any hard knobs and slice it into thin strips.

Cook

Bring the stock and the shiitake soaking liquid to a boil in a large pot over medium-high heat. Add the shiitake, wood ear and bamboo shoots and simmer for 5 minutes.
Add the pork, stirring straight away with chopsticks to separate the strands, and simmer for 2 minutes, until it is pale and cooked through. Slide in the tofu and add the light and dark soy sauce, sugar and 1/2 tsp salt. Simmer gently for 2 minutes, then taste and add more salt if it needs it.
Stir the 3 tbsp cornstarch into the 5 tbsp cold water (it settles fast, so stir again just before using). With the soup at a steady simmer, pour in about two-thirds of it, stirring, and cook for 1 minute, until the soup turns glossy and lightly coats the back of a spoon. If you like it thicker, add the rest and simmer for 1 minute more.
Turn the heat down so the soup barely simmers. Stir it once in a slow circle, then pour the eggs in a thin stream over the moving surface, ideally through the tines of a fork. Leave it completely alone for 15 seconds so the egg sets into ribbons, then stir gently once.
Turn off the heat. Stir in 4 tbsp vinegar, 1 tsp white pepper and the sesame oil, then taste: it should be distinctly sour, with the pepper catching at the back of your throat. Add more vinegar and pepper until it does, scatter with spring onion and serve, with chilli oil on the table for anyone who wants it.

Swaps

Cooking for coeliac disease or an allergy? Check every label: the notes below say which ones matter.

Gluten-free

Use tamari labelled gluten-free in place of the light soy sauce, in the marinade and the soup, and leave out the dark soy: tamari is dark enough to colour the soup. Use dry sherry instead of the Shaoxing wine, which is brewed with wheat.
Chinkiang vinegar is brewed with wheat bran, so it isn't gluten-free. Use the rice vinegar and balsamic swap from Tips, checking both labels; the sourness is a little less malty.
Check the stock and chilli oil, and make sure the cornstarch is labelled gluten-free: in some countries "cornflour" can be made from wheat.

Plant-based

Follow the vegetarian Variation (vegetable stock, no pork, 100 g more tofu and 2 more shiitake) and leave out the eggs; everything else is vegan. Check the stock and chilli oil labels.
The egg ribbons are part of the texture, so the vegan bowl is a little less silky. Cutting the extra tofu into fine matchsticks and thickening with the full amount of cornstarch helps.

High-protein

Roughly 20 g protein a bowl as written. Double the pork to 300 g (about 7 g more per bowl), marinated the same way and simmered until pale all the way through, 2–3 minutes.
Use 400 g firm tofu instead of 200 g (about 6 g more), or 4 eggs instead of 2 (about 3 g more), poured in two passes so the ribbons stay fine.

Tips

Fresh white pepper is the heat. Ground white pepper loses its punch quickly once opened, so use a fresh jar or grind whole white peppercorns. It goes in off the heat so its aroma isn't cooked away.
Never boil the vinegar. Black vinegar's aroma is volatile, and boiling flattens it to plain sourness. If you reheat leftovers, finish them with a fresh splash.
Thicken first, then add the egg at a gentle simmer. In a thickened broth the egg floats in fine ribbons; in thin, boiling soup it sinks and breaks into curds.
Cut everything the same. Thin matchsticks of pork, tofu, bamboo and mushroom cook evenly and put a bit of each in every spoonful. Pork is much easier to slice thinly after 20 minutes in the freezer.
Substitutes: for 4 tbsp Chinkiang vinegar, use 3 tbsp rice vinegar plus 1 tbsp balsamic vinegar; it's not the same, but it's close in colour and roundness. Without wood ear, double the shiitake.

Make ahead and storage

Soak the mushrooms and cut everything up to 1 day ahead, and keep it covered in the fridge.
Leftovers keep for 2 days in the fridge. Reheat gently: the soup thins as it stands, so stir in 1 tsp cornstarch mixed with 1 tbsp water if needed, then refresh it with vinegar and pepper off the heat.
Don't freeze it: the egg and tofu turn spongy.

Variations

Lily buds: dried lily buds (the dried flower buds of the day lily, sold as "golden needles") are a traditional addition. Soak 10 g in warm water for 20 minutes, snip off the hard tips and add them with the mushrooms.
Chicken: use thin strips of chicken thigh instead of pork, and simmer for 3 minutes, until opaque all the way through.
Vegetarian: use vegetable stock, leave out the pork and its marinade, and add 100 g more tofu and 2 more shiitake.
Chilli heat: for a version closer to many Sichuan restaurants, stir 1–2 tbsp chilli oil into the pot with the vinegar. The pepper should still lead.

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Hot and sour soup

Ingredients

Mushrooms

Pork

Soup

To finish