How to make
Cut the fish fillets into pieces, season them with salt and black pepper and fry them in hot oil.
Place them onto kitchen paper.
In another pan, stew the onions, add the tomatoes, a cube of butter, salt, sugar, rosemary and leave them to thicken.
In a deep frying pan put half the sauce, then the fish and again the rest of the sauce.
Add olives and cover the pan with a lid and let the appetizing stewed fish cook for 10-15 minutes.
Serve the whitefish in tomato sauce with a garnish of rice or a fresh salad.