Slice the flank steak thinly against the grain and marinate with soy sauce, peanut oil, cornstarch, and optional baking soda for 10 minutes.

In a small bowl, whisk together chicken stock, Shaoxing wine, dark soy sauce, brown sugar, and cornstarch until smooth to make the sauce.

Boil water in a nonstick skillet, add chopped broccoli, and steam for 1 minute until bright green. Remove and set aside.

In the same skillet, heat peanut oil over high heat, add marinated beef and sear for 30 seconds. Flip and cook for another 20-30 seconds.

Stir in minced garlic and ginger, sauté for 30 seconds until fragrant.

Add the steamed broccoli and sauce to the skillet, mix well, and cook for 1 minute until the sauce thickens.