Beat the flour, egg and water well until you have a thick, smooth batter.
Dry off the prawns, dip them into the batter and pop them, in batches, into the heated oil in a large frying pan.
Fry for just under a minute or until lightly golden.
Drain on paper towels and keep warm in a very low oven while cooking other batches.
Serve with a big bowl of habanero and ginger jam, or with lime wedges.
Rice flour is available from leading supermarkets - you'll find it on the health food shelves.