Hot and sour soup (Suanla tang)

1. Soak the wood ear mushrooms in lukewarm water for 20 minutes, then cut into strips; cut the pork leg, tofu and bamboo shoots into thin matchsticks.

2. Bring the water to the boil, add the pork, mushrooms and bamboo shoots and simmer for 5 minutes.

3. Add the tofu, soy sauce and salt and simmer for another 2 minutes.

4. Mix the cornflour with the 4 tablespoons of cold water and pour it into the soup, stirring constantly; simmer for 1 minute until slightly thickened.

5. Beat the egg and pour it in a thin stream while slowly stirring the soup, so fine egg ribbons form; turn off the heat.

6. Stir in the black rice vinegar and white pepper, drizzle with sesame oil, sprinkle with spring onions and serve piping hot.

Tip: The heat of this soup comes not from chilli but from white pepper – so stir it in at the end, off the heat, to keep its aroma. It's also great vegetarian: leave out the pork and add a few dried shiitake.