Steps
1. In a bowl, marinate the beef strips with soy sauce and oyster sauce for 15 minutes.
2. Heat sesame oil in a pan over medium-high heat. Add minced garlic and stir-fry until fragrant.
3. Add the marinated beef strips and cook until browned.
4. Toss in the sliced bell pepper and onion, stir-fry for a few minutes until vegetables are tender.
5. Season with salt and pepper to taste.
6. Serve the beef stir-fry over cooked rice, garnish with chopped green onions.