Instructions

1. Debeard and wash the mussels thoroughly, then put them in a large bowl. Discard those that stay open even after tapping their shall on side of the bowl.
2. Peel and finely slice the spring onions and the garlic. Cut the lemongrass in half vertically, then halve again.
3. Cut off the coriander stalks, chop them finely and put aside the leaves. Deseed and finely chop the chilli.
4. Heat a spoonful of groundnut oil in a large casserole dish and gently soften the spring onion, garlic, coriander stalks, lemongrass and most of the chilli for about 8-10 minutes.
5. Add the coconut milk and fish sauce, then bring to the boil and add the mussels.
6. Put the lid on and cook for 5 minutes or so, until all the mussels have opened up. Discard any unopened ones.
7. Squeeze some lime juice over it then scatter the coriander leaves and the remaining chilli.
8. Serve hot.