In a mixing bowl, combine the sliced flank steak with baking soda, Shaoxing wine, light soy sauce, oyster sauce, white pepper, water, and cornstarch. Coat the meat evenly and let it marinate for at least 15 minutes at room temperature.

In a separate small bowl, whisk together the oyster sauce, light soy sauce, dark soy sauce, Shaoxing wine, granulated sugar, low sodium chicken broth, and cornstarch until smooth. Set aside.

Bring a large pot of water to a boil. Add the broccoli florets and cook for 1-2 minutes until tender-crisp. Drain and rinse with cold water to stop cooking.

Heat a wok over medium-high heat and add oil. Sear the marinated beef for 30 seconds per side until browned. Keep warm on a plate.

In the same wok, sauté minced garlic and ginger for 30 seconds until fragrant. Add cooked broccoli and stir-fry for another minute.

Return the beef to the pan, add the stir-fry sauce, and toss to combine. Cook for an additional 1-2 minutes until the sauce thickens.

Stir in toasted sesame oil, mix well, and serve hot over steamed rice.