1. Shell and devein the prawns and remove all inedible parts.
2. Heat the stock in a pot. When it is boiling, put in the lemon grass and then the prawns. Season with the fish sauce, chilies, and lime juice. Then, add the kaffir lime leaves remove from the heat, and serve hot.
Note: Ground dried chilies can be substituted for the hot chilies in this recipe ; add 1 teaspoonful of ground dried chilies to the boiling stock.