Put the red chilli, paprika, curry powder, garlic, shallot, chopped lemon grass and chopped ginger in a blender and blitz until smooth. You may need to add some water to help blend the mixture.
Transfer to a bowl, add the prawns and leave to marinate overnight. Put the prawns on metal skewers and barbecue for 2-3 minutes each side. Sprinkle with coriander and serve with lemon wedges.