I always think beef and onion are good friend, especially in stir-fry.

1. Prepare beef slices. Put them in a small bowl. Season with a little salt and black pepper. Then add in 1/2 tsp light sou sauce and 1-2 tsp starch. Mix them well.
2. Heat a pan. Add in 1 tablespoon oil. When oil is heated, add beef into the pan. Quickly separate them to let them not stick to each other.
3. When beef is no more pinkish, add in onion slices and green chili. Stir fry for 1 minute or 2.
4. Add in 1 tsp oyster sauce. Stir fry evenly.

Ready to serve. Very simple and quick.