Slice the flank steak against the grain into thin strips, about 1/4 inch thick. In a bowl, combine the sliced beef with soy sauce, peanut oil, and cornstarch. Allow to marinate for at least 10 minutes.

Prepare the sauce by combining chicken stock, Shaoxing wine, dark soy sauce, and brown sugar in a mixing bowl. Whisk until the sugar dissolves, set aside.

Bring 1/4 cup of water to a boil in a large skillet. Add the broccoli, cover, and steam for about 1 minute until tender-crisp. Remove and set aside.

Wipe the skillet, add peanut oil, and heat on high. Add the marinated beef in a single layer, sear for 2-3 minutes until browned, then flip and cook for another 2 minutes.

Add minced garlic and grated ginger to the skillet, stir for about 30 seconds until fragrant.

Return the steamed broccoli to the skillet and pour the sauce over. Toss gently and cook for another minute until the sauce thickens.

Transfer to a serving platter and enjoy hot over rice or noodles.