Prepare the Beef: Place the sliced flank steak in a mixing bowl. If using baking soda, dissolve it in water and massage into the meat until fully absorbed. Add cornstarch, oil, and oyster sauce, mixing thoroughly to coat the beef evenly. Let it marinate for at least 30 minutes.

Make the Sauce: In a separate bowl, combine the chicken stock, soy sauces, oyster sauce, sugar, sesame oil, and white pepper. Stir well and set aside.

Blanch the Broccoli: Bring a pot of water to a rolling boil. Submerge the broccoli florets and blanch for 30 to 60 seconds, depending on your preferred texture. Drain and set aside.

Cook the Beef: Heat a wok over high heat until it reaches a smoking point. Add two tablespoons of vegetable oil and immediately introduce the marinated beef. Sear on both sides for 2 to 3 minutes until browned. Turn off the heat, remove the beef from the wok, and set it aside.

Sauté the Aromatics: Reduce the wok to medium heat and pour in the remaining tablespoon of vegetable oil. Add the minced garlic and ginger, stirring for about 5 seconds until fragrant. Carefully drizzle the Shaoxing wine along the wok's perimeter to deglaze and enhance the dish’s depth of flavor.

Thicken the Sauce: Pour the prepared sauce mixture into the wok, stirring along the sides to incorporate any residual flavors from the beef. Allow the sauce to reach a simmer. Stir the cornstarch slurry well before gradually incorporating it into the sauce, stirring continuously. Let it cook for about 20 seconds until thickened.

Combine and Serve: Return the seared beef and its juices to the wok, followed by the blanched broccoli. Toss everything together over medium heat, ensuring the sauce evenly coats all components. If the sauce is too thin, increase the heat to reduce it slightly or add a bit more cornstarch slurry. If too thick, adjust with a small splash of chicken stock or water. Serve immediately with steamed rice for a complete meal.