Prepare the beef: Slice beef thinly against the grain. In a bowl, combine beef with 1 tbsp soy sauce, 1 tbsp Shaoxing wine, 1 tbsp cornstarch, 1/2 tsp baking soda (if using), 1 tsp sesame oil, and 1 egg white. Mix well and let marinate for at least 15-20 minutes at room temperature, or up to 30 minutes in the refrigerator.

Make the stir-fry sauce: In a small bowl, whisk together 2 tbsp soy sauce, 1 tbsp oyster sauce, 1 tbsp rice vinegar, 1 tsp sugar, 1 tsp cornstarch, and 1/4 cup chicken broth. Set aside.

Cook the beef: Heat 1 tbsp vegetable oil in a large wok or skillet over high heat. Add the marinated beef in a single layer (cook in batches if necessary to avoid overcrowding). Stir-fry for 1-2 minutes per side until lightly browned and cooked through but still tender. Remove beef from the wok and set aside.

Stir-fry vegetables: Add the remaining 1 tbsp vegetable oil to the wok. Add minced garlic and grated ginger and stir-fry for 30 seconds until fragrant. Add broccoli florets and bell pepper slices. Stir-fry for 3-5 minutes until vegetables are crisp-tender.

Combine and sauce: Return the cooked beef to the wok with the vegetables. Give the prepared stir-fry sauce a quick whisk (cornstarch settles) and pour it over the beef and vegetables. Stir constantly for 1-2 minutes until the sauce thickens and coats everything evenly.

Serve: Remove from heat. Serve immediately over cooked rice, garnished with sesame seeds and sliced green onions if desired.