Marinate the Beef:
In a mixing bowl, combine the sliced beef with soy sauce and cornstarch. Stir well to coat the meat evenly. Let it sit for 15 minutes to absorb the flavors.
Cook the Beef:
Heat 1 tablespoon of oil in a wok or large pan over medium-high heat. Add the marinated beef and stir-fry until browned. Remove from the pan and set aside.
Sauté the Vegetables:
Add the remaining tablespoon of oil to the same pan. Toss in the sliced onion, green bell pepper, and red bell pepper. Stir-fry until they begin to soften but still have a slight crunch. Add the minced garlic and cook for another minute.
Combine and Finish:
Return the beef to the pan. Add oyster sauce, sugar, black pepper, and beef broth. Stir everything together and cook for 2–3 more minutes, until the sauce thickens slightly and coats the beef and vegetables evenly.
Serve:
Dish up hot with rice or your favorite side. Enjoy!
