Steps
1. In a bowl, combine the beef, soy sauce, oyster sauce, and cornstarch. Mix well and set aside.
2. Heat the vegetable oil in a wok or large skillet over high heat.
3. Add the minced garlic and stir-fry for 1 minute until fragrant.
4. Add the sliced onion, bell pepper, carrot, and broccoli. Stir-fry for 3-4 minutes until the vegetables are crisp-tender.
5. Push the vegetables to one side of the wok and add the marinated beef. Stir-fry for 2-3 minutes until the beef is cooked to your desired level of doneness.
6. Season with salt and pepper to taste.
7. Serve the beef stir-fry hot with steamed rice or noodles.