I have a real big soft spot for hot & sour soup. When I was a kid in Hong Kong my dad used to buy a particular brand that came in a foil pouch, which you could just stick in a pot of boiling water to heat up. It came out just as you and I know it; slightly gloopy from cornflour, with bits of mushroom and char siu, sometimes peas floating about in it. We always added more vinegar to pep it up. It really hit the spot.
All over Asia countries have their version of hot and sour soup. In Thailand, tom yum soup is a clear broth flavoured with lemongrass and lime leaves, sometimes with chicken (tom yum gai), sometimes with prawns (tom yum goong). I have a recipe in my book, Chinatown Kitchen which you can buy here, plug plug, for my ultimate tom yum made with a secret ingredient. The Filipinos also have their own version, as do the Vietnamese.
Traditionally, the Chinese version of hot & sour soup originates from Beijing or Sichuan, and pigs blood is used to thicken the broth. What with it being rather difficult to find here, and perhaps not immediately appealing, instead most Chinese restaurants use cornflour to thicken it, giving it that characteristically gloopy appearance, or it is thickened egg-drop style - that is, whisked egg is stirred slowly into the soup and the strands are suspended within the broth. Contrary to popular belief, white pepper is used for the 'hot' aspect of the soup, not chillis.
This Hunanese version is thickened by dried rice noodles cooked directly into the pot, so the excess starch thickens the soup. Chilli bean paste gives a richer, deeper hotness, though the white pepper also features. Pickled mustard greens give it that extra wallop of the sour balance. It's a great one-dish meal; after all the initial chopping it is quick to cook. Always add the black vinegar at the end, otherwise it loses its delicate flavour easily. You can add leftover roast meats like chicken or pork to this too, but it's just as filling in its vegetarian (and even vegan) state.
Hunanese Hot & Sour Noodle Soup
1/2 block of firm tofu, chopped into cubes
1.5 litres of vegetable or chicken stock
4 shiitake mushrooms, soaked in hot water for 15 minutes, stems removed and slivered
2 pieces of woodear fungus, soaked in hot water for 10 minutes and shredded
A handful of sugarsnap peas, julienned
3 tbsp pickled mustard green, rinsed well in water
A bundle of enoki mushrooms, stems cut into three pieces
2 cloves of garlic, minced
1 inch of ginger, peeled and minced
2 tbsp chilli bean paste
2 tbsp light soy sauce
4 tbsp Chinkiang black vinegar
1 tsp white pepper
1 spring onion, greens and whites separated, julienned
1 large red chilli, sliced into rings
250gr dried rice noodles - I used 8mm size
1 tbsp cooking oil
In a large saucepan, heat up the oil on a medium heat. Add the garlic and ginger and whites of the spring onions and stir-fry until fragrant. Add the chilli bean paste, stir well, then all the mustard greens, shiitake mushrooms and the woodear fungus. Add the chicken stock and simmer for 10 minutes.
Add the soy sauce, then add the noodles. Stir well, making sure the noodles are covered with liquid. Cook according to the packet instructions - mine took about 10 minutes of simmering to become soft. Stir every couple of minutes. When the noodles are soft, add the tofu and simmer for another 3 minutes, then add the sugarsnap peas and enoki mushrooms and place a lid on top. Take off the heat and leave to stand for 5 minutes.
Serve equally into 4 bowls and add the black vinegar and a hefty pinch of white pepper on top of each, with a little greens of the spring onion garnish. Finally, add a few chilli rings to each bowl. I usually bring the vinegar and some chilli oil to the table, in case people prefer to adjust their soups themselves.