Wash the fish in cold water, place in a pan and simmer gently in 4 cups of water until the water is almost evaporated.
Drop the tomatoes into boiling water and peel, the chop the tomatoes.
In a frying pan, heat the oil, then stir in the onions and tomatoes and cook gently until soft.
Add the cooked fish and salt, stir gently with extra caution not to crush the fish.
Add the milk and simmer, about 30min, the milk forms the gravy.
Serve with ugali or rice.