Stir-fried beef with coriander is as follows:
1. First, fry the beef and put it on the plate.
2. Then put the onion, green pepper and red pepper into the pot and stir-fry until cooked.
3. Pour the beef and stir fry with the onion.
4. Add the coriander and stir fry.
5. Add black pepper and salt according to taste.