Slice each tofu cake diagonally to make 8 triangles. With each triangle, make a slit on the cut side to make a pocket for stuffing. Hollow out some tofu from the pocket.
In a bowl, mix well the hollowed out tofu pieces with minced prawns, chicken, green onions, sesame oil, cornflour, egg and season with salt and pepper.
Carefully stuff the tofu triangles with the filling, making a slight mound on the outside of slit. Place the triangles in a steamer and steam for 20 minutes.
Meanwhile make the dipping batter by combining the egg with flour and pouring enough water while whisking until you've reached a medium-thin consistency.
Make the sauce: Chop the roasted peanuts until medium coarse and add all the ingredients together in a bowl. Stir until the sugar and salt has dissolved. Set aside.
When the triangles are cooked, remove from steamer. Heat oil in wok until hot. Take each triangle in batches, and dip in batter and slowly lower in hot oil. Fry until golden brown and batter is cooked. Drain on paper towel.