Begin by slicing the flank steak against the grain into ½ inch strips. In a mixing bowl, combine the beef with soy sauce, peanut oil, and cornstarch. Let it marinate for at least 10 minutes.

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

In a skillet, bring a small amount of water to a boil. Add the broccoli florets, cover, and steam for about 1 minute until just tender. Set aside.

Heat peanut oil in the same skillet over medium-high heat. Add the marinated beef and cook in a single layer for about 30 seconds until browned. Flip and cook for another 1-2 minutes.

Add minced garlic and grated ginger to the skillet, cooking for about 30 seconds until aromatic. Then add the steamed broccoli and prepared sauce, stirring to coat everything evenly.

Cook for another minute to allow the sauce to thicken. Serve hot over rice or noodles.