Soak the clams in a large bowl of cold water for about 15 minutes to remove any sand or grit, then rinse under cold running water.
Put the clams in a heatproof dish that will fit inside your wok. Pour the wine over them and add the lemongrass and chilli. Place the dish in the wok, then pour enough water into the wok to come halfway up the sides of the dish.
Place the wok over a medium heat, cover and cook the clams for about 15 minutes.
Carefully remove the dish from the pot and discard any clams that haven,t opened. Spoon into a serving dish and garnish with coriander and mint. Serve immediately.