3 fresh kaffir lime leaves or 3 pieces of lime rind
2 Thai red chillies, halved and deseeded
2 tablespoons lime juice
2 tablespoons Thai fish sauce
50 g (2 oz) can bamboo shoots
125 g (4 oz) oyster mushrooms
2 spring onions, finely sliced
½ red chilli, sliced, to garnish
Pour the stock into a saucepan and add the lemon grass, lime leaves or rind and chillies. Simmer for 10 minutes.
Strain the liquid into a clean saucepan. Reserve a little red chilli and discard the remaining seasonings. Add the lime juice and fish sauce to the soup with the bamboo shoots and mushrooms and reserved chilli.
Simmer the soup for 5 minutes, then ladle into 4 warm bowls and sprinkle with the spring onions. Serve garnished with red chilli slices.