Preparation materials: pork tenderloin 300g, pineapple 100g, half red pepper, half green pepper, egg 1 piece, and a little flour; Seasonings needed for curing tenderloin: a little salt, soy sauce, pepper, cooking wine; Seasoning of sweet and sour sauce: 3 tablespoons of tomato sauce (canned tomato sauce is available. ), 2 tbsps of vinegar, 2 tbsps of sugar, 2 tbsps of soy sauce1/,half a cup of water, and proper amount of starch. Practice: wash the pineapple, cut it into small pieces and soak it in light salt water; Wash red pepper and green pepper, remove pedicels and seeds, and cut into diamond-shaped slices; Wash tenderloin and cut into large pieces of about 2 cm. Take a small bowl and adjust the juice according to the seasoning needed for the sweet and sour sauce. Add salt, soy sauce, pepper and cooking wine to the tenderloin, stir well and marinate for a while. Coat the marinated meat with a layer of egg liquid, then soak the flour evenly, and shake off the excess flour with a filter. Pour an appropriate amount of oil into a small milk pot, heat it to 50%, put the meat pieces in one by one and fry them until golden brown, then take them out. Then heat the oil on the fire, pour the meat into it and fry it again, only once. Put the wok on the fire, pour the prepared sauce directly without oiling, add water starch after boiling, and pour pineapple, red pepper slices, green pepper slices and fried tenderloin after the sauce thickens, so that these materials can be evenly sauced, and green pepper and red pepper can be eaten raw without oiling in advance or frying until soft.