Make diagonal cuts on both sides of the fish. Bring some water to a boil in a wok, turn off the heat and drop the fish in briefly; take them out almost immediately. Toss the fish with lemon juice and place them on a banana leaf.
Heat a little oil in a pan, add ginger, garlic, curry leaves, onions and cili padi and stir together; stir in soy sauce and oyster sauce (add water if it´s too thick), then pour the mix on top of the fish. Cover with another banana leaf and steam for 10 minutes (the water must be boiling before you start steaming). To check if the fish are done, poke the thickest part of the flesh with a chopstick - it should penetrate the skin. Sprinkle with a bit more soy sauce, garnish with chopped coriander if you like, and eat with rice.