1 - step 1 Bring the stock to a boil in a medium-sized saucepan.

2 - Add the lemongrass, galangal, coriander roots and lime leaves, then simmer for 2 mins.

3 - step 2 Add the prawns, fish sauce, chillies and lime juice, then return to the boil.

4 - Taste and adjust the seasoning with either more lime juice or fish sauce, then garnish with coriander leaves and serve.