To make this dish even faster, use ready-to-cook mussels, available from the seafood section of your supermarket.
2 cups water
600g mussels, cleaned, bearded
2 Tbsp vegetable oil
2 Tbsp lemongrass, finely chopped
3 eschalots, finely diced
1 Tbsp minced garlic
4 coriander roots, cleaned and finely chopped, stems chopped and leaves reserved
270ml light coconut milk
2 kaffir lime leaves, very finely sliced
1 Tbsp palm sugar, grated or pounded, plus extra
2 Tbsp fish sauce, plus extra
½ tsp freshly ground white pepper, plus extra
1 long red chilli, finely sliced
½ bunch Vietnamese mint
Put water in a large saucepan or wok and bring to boil over high heat. Add mussels, cover and cook just enough to open the mussels, but not fully cook. Drain mussels and set aside.
Put oil in a preheated wok set over high heat. Add lemongrass and cook for a few minutes until fragrant. Add eschalot, garlic and coriander root. Cook for a further 2 minutes. Stir in coconut milk, kaffir lime and palm sugar and bring to a gentle simmer, then add fish sauce. Toss mussels in hot broth and cook for 1 minute.
Add pepper and toss through coriander stems and chilli. Taste broth and balance with more fish sauce, pepper or sugar. Take to the table and serve or divide the mussels and broth into individual serving bowls. Scatter over Vietnamese mint and reserved coriander leaves to serve.