Slice chillies down the centre. Remove seeds and chop finely. Add chillies, palm, fish sauce and lime juice and stir lightly.
Combine all filling ingredients in a large bowl. Fill a shallow dish (large enough to hold a rice paper wrapper) with warm water. Dip wrapper into the water one at a time, leaving for 1 minute or until soft. Drain and place onto a clean tea towel.
Place a small handful of the filling across the base of the wrapper. Top with 2 prawn halves, then fold in the sides and roll up. Repeat with the remaining wrappers and filling.