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

Prepare the stir-fry sauce by mixing together oyster sauce, light soy sauce, dark soy sauce, Shaoxing wine, sugar, chicken broth, and cornstarch in a bowl. Stir until well combined and set aside.

Bring a pot of salted water to a rolling boil. Add the broccoli florets and blanch for 1-2 minutes. Quickly drain and plunge into an ice bath.

Heat vegetable oil in a wok over high heat. Add the marinated beef and sauté for about 30 seconds on each side until browned. Remove the beef and set aside.

In the same wok, add more oil if needed, minced garlic and grated ginger. Stir-fry for 30 seconds until fragrant.

Add the blanched broccoli and stir-fry for about 1 minute. Return the beef to the wok, pour in the stir-fry sauce, and cook for an additional 1-2 minutes until the sauce thickens.

Finish with a drizzle of toasted sesame oil and serve immediately over fluffy white rice.