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

While the beef marinates, prepare the stir-fry sauce by mixing oyster sauce, light soy sauce, a splash of dark soy sauce, Shaoxing wine, sugar, chicken broth, and cornstarch in a bowl until smooth.

Bring a pot of salted water to a boil and add the broccoli florets. Blanch for 1-2 minutes until bright green and crisp-tender. Drain and set aside.

Heat a wok or large skillet over medium-high heat. Add a drizzle of oil and once hot, add the marinated beef in a single layer. Cook for about 30 seconds on each side until browned, then remove from the wok.

In the same wok, add a bit more oil if necessary and toss in minced garlic and ginger. Sauté for about 30 seconds until fragrant.

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

Before serving, drizzle sesame oil over the stir-fry and serve over rice or quinoa, garnished with green onions if desired.