Mix together all the ingredients to make the marinade. Toss the prawns in it and chill in the fridge for half an hour.
If you are using bamboo skewers, soak in water to stop them burning.
Thread three prawns onto each skewer, saving the excess marinade. Grill over a hot griddle or barbecue, turning once or twice, and brush with the marinade as you go. Just 2-3 minutes should do