In a bowl, combine thinly sliced flank steak with baking soda, Shaoxing wine, light soy sauce, oyster sauce, white pepper, water, and cornstarch. Mix thoroughly and let marinate for at least 15 minutes.

In a separate bowl, whisk together the oyster sauce, light soy sauce, dark soy sauce, Shaoxing wine, sugar, chicken broth, and cornstarch for the stir-fry sauce.

Bring a pot of salted water to a rapid boil. Add broccoli florets and cook for 1-2 minutes. Drain and shock in ice water.

Heat 2 tablespoons of cooking oil in a wok over medium-high heat. Sear the marinated beef for about 30 seconds on each side until browned.

Add another tablespoon of oil to the wok along with minced garlic and ginger. Sauté for about 30 seconds.

Add blanched broccoli, seared beef, stir-fry sauce, and cook for 1-2 minutes until sauce thickens.

Drizzle with toasted sesame oil and garnish with diced green onions before serving.