Wrap foil around pairs of skewers and barbecue for 2-3 minutes on each side. Remove the foil and barbecue for a further 30 seconds to gently colour. Garnish the mango salsa with the mint leaves and serve with the prawns.
Put the egg in a small bowl, and put the coconut and black pepper on a plate. Dip the prawns into the egg, then roll in the coconut and black pepper mixture to coat. Thread 2-3 prawns onto each skewer.
Preheat the barbecue. Make the salsa: mix the mango with the chopped mint, chilli, lime juice and zest. Set aside.