Begin by slicing your flank or skirt steak against the grain into thin strips. In a mixing bowl, combine the beef with soy sauce, peanut oil, and cornstarch. Mix well and let it marinate at room temperature for about 10 minutes.

While the beef is marinating, whisk together chicken stock, Shaoxing wine, dark soy sauce, brown sugar, and cornstarch in a separate bowl. Set the sauce aside.

In a large nonstick skillet, bring about an inch of water to a rolling boil over medium-high heat. Add the broccoli florets and steam them for just 1 minute until bright and crisp. Remove and set aside.

Return the skillet to heat and add a drizzle of peanut oil. Once hot, add the marinated beef in a single layer and let it sear for 30 seconds before flipping to brown the other side, stir-frying until cooked through (about 2-3 minutes).

Push the beef to one side of the skillet, add minced garlic and ginger to the cleared space, and stir-fry for about 30 seconds until fragrant.

Return the steamed broccoli to the skillet with beef and aromatics, pour the prepared sauce over everything, and gently toss to coat. Stir until the sauce thickens and becomes glossy, about 1-2 minutes.