Combine all the marinade ingredients in a bowl. Pour the marinade over the prawns ensuring the prawns are well coated with the marinade. Marinate for 30 mins. at room temperature or 2 hours in the refrigerator.
Drain the prawns and reserve the marinade.
Thread 3-4 prawns on a wooden skewer. Thread so as to pierce each prawn twice. Barbeque over medium hot coals, until the prawns are pink.
Combine the reserved marinade with the coconut milk in a pan and heat over the barbeque for 5-6 mins, until the sauce thickens.