Combine minced pork, onion and crabmeat in a mixing bowl. Beat 1 egg with the cornflour and stir into the pork mixture. Add salt, pepper and light soy sauce. Divide the mixture into 2 equal portions.
Sandwich each portion between 2 slices of bread. Arrange them on a steaming rack. Steam for 12-15 minutes. Remove and leave aside to cool completely.
Beat the remaining eggs in a shallow plate or dish and dip the sandwiched roti babi into the eggs. Deep-fry the pieces in two batches over low heat until both sides are golden brown. Dish out and drain from oil. Serve roti babi with the dipping sauce.