In a bowl, combine the sliced steak with 2 tablespoons of soy sauce, oyster sauce, 1 tablespoon of cornstarch, and rice wine. Toss to coat and let it marinate for 15–20 minutes.
Heat 1 tablespoon of vegetable oil in a large wok or skillet over high heat until shimmering.
Add the marinated beef to the hot pan in a single layer. Sear for about 2-3 minutes, stirring occasionally, until browned but not fully cooked. Remove the beef from the pan and set aside.
In the same pan, add another tablespoon of oil. Stir-fry the sliced onions and bell peppers for 2–3 minutes until they are slightly tender but still crisp.
Add the minced garlic and ginger to the pan and sauté for an additional 30 seconds until fragrant.
Return the beef to the pan. Pour in the broth, 1 tablespoon of soy sauce, and freshly ground black pepper. Stir to combine.
If desired, mix 1 tablespoon of cornstarch with 2 tablespoons of water to create a slurry. Add this to the pan to thicken the sauce, stirring until the sauce reaches your desired consistency.
Drizzle the sesame oil over the dish for added flavor and toss everything together. Serve hot, ideally over steamed rice or noodles.