Steps for making Braised Spanish Mackerel in Tomato Sauce：Prepare the Spanish mackerel and cut it into pieces. Add oyster sauce, soy sauce, cumin powder, shredded ginger, and salt for seasoning and marinating. Sprinkle a thin layer of flour on both sides of the fish pieces. Deep-fry over medium heat in hot oil. Fry until both sides are golden brown, then remove and set aside. Add an appropriate amount of salt to tomato ketchup, along with a little water and cornstarch to make a thickened sauce. After bringing to a boil, add the fried fish pieces. Turn up the heat to reduce the sauce, and it is ready to serve.