Butterfly the prawns by slicing from the tail to the front of the prawns. Do not cut all the way through.
Marinate prawns with Chinese cooking wine, salt and pepper for 10 minutes.
Remove the tough outer leaves, upper stalk and the bulb of the lemongrass. Bash with a kitchen mallet and then cut into 3-inch sections.
In a hot wok, fry ginger, shallot, garlic, lemongrass and chilies until they are aromatic. Then add prawns and cook for 3-4 minutes. Then add fish sauce, sugar and lime juice.