Ingredients: beef 300g, vinegar 10g, chopped green onion, corn flour 50g, salt 500g, monosodium glutamate, chicken essence, sugar, soup stock, peanut oil and pepper. Methods: 1. Slice beef, wash corn flour and pat it hard for about 5 minutes, add a little peanut oil and stir. 2. Put oil in the wok, heat it, add broth and appropriate amount of water, add appropriate amount of salt, monosodium glutamate, chicken essence and sugar, after the water boils, put the beef into boiling water one by one, and cook it at medium heat 1 min. 3. Put the vinegar and chopped green onion into the soup bowl, put the cooked beef into the bowl and sprinkle some pepper.