Marinate the Beef : Slice the flank steak thinly against the grain into bite-sized pieces. In a bowl, combine the soy sauce, cornstarch, Shaoxing wine, baking soda, white pepper, and vegetable oil. Add the sliced beef and mix well to coat. Let the beef marinate for 10–15 minutes while you prepare the other ingredients.

Prepare the Stir-Fry Sauce : In a small bowl, whisk together the black bean garlic sauce, oyster sauce, sugar, Shaoxing wine, sesame oil, cornstarch, and chicken stock. Set aside.

Cook the Vegetables : Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat. Add the minced garlic, sliced ginger, and diced red bell pepper. Stir-fry for 1 minute until fragrant. Add the snow peas and stir-fry for an additional minute. Transfer the vegetables to a plate and set aside.

Cook the Beef : In the same skillet, add a little more oil if needed and turn the heat to high. Add the marinated beef in a single layer and cook for 1–2 minutes without stirring to sear one side. Flip the beef pieces and cook for another minute until browned but still tender.

Combine and Finish : Reduce the heat to medium and return the cooked vegetables to the skillet. Stir to combine. Give the prepared stir-fry sauce a quick whisk and pour it into the skillet. Add ¼ cup of cold water to loosen the sauce if needed. Stir everything together and cook for 1–2 minutes until the sauce thickens and evenly coats the beef and vegetables.

Serve : Remove from heat and serve the stir-fry hot over steamed rice or noodles. Garnish with sesame seeds or sliced green onions if desired.