To make batter, combine rice flour, coconut milk, eggs and salt. Heat some oil in a 20cm pan (preferably non-stick) add enough batter to coat base. Cook for 2 minutes. Repeat with remaining batter. Put all pancakes aside.
To make filling, blend ginger, garlic, soy and white sauce. Add crab meat, mushrooms, spring onions and bean sprouts and season to taste. Place a spoonful of the mixture on to each pancake. Tuck in ends and roll up so mixture doesn't escape.
Carefully roll each pancake in seasoned flour then in beaten egg. Deep-fry until golden. Serve on lettuce leaves, sprinkled with chopped coriander, accompanied by nuoc cham.
