1. Prepare the Beef

Start by slicing the beef thinly against the grain, which ensures tender pieces. In a bowl, combine soy sauce, Shaoxing wine, cornstarch, and sesame oil. Add the beef slices to the marinade, mixing to coat evenly. Cover and let it marinate for at least 10 minutes while you prepare the other ingredients.

2. Mix the Sauce

In a small bowl, whisk together the soy sauce, oyster sauce, dark soy sauce (if using), sugar, white pepper, and beef broth. Set aside. This step ensures the sauce is ready to pour when needed, keeping the stir-fry process seamless.

3. Cook the Onions

Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat. Add the sliced onions and stir-fry for 3-4 minutes, or until they’re softened and slightly caramelized. Remove the onions from the pan and set them aside.

4. Sear the Beef

In the same skillet or wok, add the remaining 1 tablespoon of vegetable oil. Turn the heat to high and add the marinated beef in a single layer. Sear the beef for about 1 minute on each side until browned. Avoid overcrowding the pan; cook in batches if necessary. Remove the beef and set aside.

5. Combine and Cook

Lower the heat to medium and add the garlic and ginger to the skillet. Stir-fry for 30 seconds until fragrant. Return the cooked onions and beef to the pan. Give the sauce a quick stir and pour it into the skillet. Toss everything together to coat the beef and onions in the sauce.

6. Thicken the Sauce

Stir the cornstarch slurry into the skillet and mix until the sauce thickens and becomes glossy, about 1 minute. Taste and adjust seasoning if needed.

7. Garnish and Serve

Transfer the stir-fry to a serving dish and garnish with green onions and sesame seeds if desired. Serve hot with steamed rice or noodles.