Prepare the ingredients you need. Wash onion and pepper, shred and soak in water. Cut a knife on the back of mandarin fish. Rub cooking wine on both sides of the fish, sprinkle salt evenly, put ginger or ginger slices, and put ginger slices into the fish belly. Pour an appropriate amount of water into the pot to boil in advance, and steam the mandarin fish in the pot for about 10 minute. Drain the steamed fish, drizzle with soy sauce, and add shredded onion and pepper. Pour cooking oil into the pot and burn it until it smokes slightly. Pour the cooked cooking oil into mandarin fish and enjoy.