Steps
1. Heat oil in a wok or skillet over high heat.
2. Add the beef and cook until browned, then remove from the pan and set aside.
3. In the same pan, add the bell pepper, onion, and garlic. Stir-fry for 2-3 minutes until the vegetables are slightly softened.
4. Return the beef to the pan and add the soy sauce, oyster sauce, black pepper, and salt. Stir-fry for another 2-3 minutes until everything is well coated and heated through.
5. Serve hot with steamed rice or noodles.