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

In a separate small bowl, mix together oyster sauce, light soy sauce, dark soy sauce, Shaoxing wine, sugar, chicken broth, and cornstarch until well combined.

Bring a pot of salted water to a boil. Once boiling, add the broccoli florets and blanch for about 1–2 minutes until bright green and still crisp. Drain and set aside.

Heat a wok or large skillet over medium-high heat, add oil, and then the marinated beef. Sear for about 30 seconds on each side until browned, then remove and set aside.

In the same pan, add minced garlic and ginger, stirring for about 30 seconds until fragrant. Next, toss in the blanched broccoli and stir-fry for an additional minute.

Return the beef to the pan, pour in the stir-fry sauce, and toss until the sauce thickens and coats the ingredients.

Remove from heat, drizzle with toasted sesame oil, mix well, and serve hot over steamed rice.