Remove the head, gut and scales of the milkfish. Rinse.
Place fish, onion, tomato, ginger, lime juice, soy sauce in a bowl and marinate for 5 minutes.
Bake fish uncovered in a 350F/180C oven for 35 minutes.
Pour marinade over fish and cook for 5 minutes.
Serving Suggestions: Serve this dish with white rice. Enhance the flavour with a dipping sauce such as soy sauce with lime.