Place mince in a saucepan with water, fish sauce, and lime leaves and break up with a wooden spoon. Heat over a medium heat and keep stirring from time to time to separate. Once all of the prawn has cooked, transfer to bowl, mix through the chilli powder and leave for 10 mins to cool down a little.
Tear the herbs and add to the mince along with all of the rest of the ingredients reserving a little of the ground rice and sliced lime leaf to garnish the top with. Place in the 8 lettuce cups and top with reserved ground rice and lime leaf julienne.