In a bowl, combine the sliced beef with cornstarch, soy sauce, and half of the ground black pepper. Mix well and let it marinate for at least 15 minutes.
Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat. Add the marinated beef and stir-fry for about 3-4 minutes until it’s browned and just cooked through. Remove the beef from the skillet and set aside.
In the same skillet, add another tablespoon of vegetable oil. Sauté the minced garlic and grated ginger for about 30 seconds until fragrant.
Add the sliced bell pepper and broccoli florets to the skillet. Stir-fry for about 3-4 minutes until the vegetables are tender-crisp.
Return the cooked beef to the skillet, along with oyster sauce and the remaining black pepper. Stir everything together for another minute until well combined, and heated through.
Remove from heat and garnish with chopped green onions before serving.
Serve the stir fry hot over cooked jasmine rice.
Notes
Serve the stir fry in a large bowl, topped with extra green onions and a sprinkle of sesame seeds for a pop of flavor and texture.