Begin by slicing the flank steak thinly against the grain. In a medium bowl, combine the sliced beef with soy sauce, peanut oil, and cornstarch. Mix well and let it marinate for at least 10 minutes.

In a separate bowl, whisk together chicken stock, Shaoxing wine, both soy sauces, brown sugar, and an additional tablespoon of cornstarch.

Fill a large skillet with about an inch of water and bring it to a boil over medium-high heat. Steam the broccoli for about 1 minute until bright green and crisp-tender.

In the same skillet, heat a tablespoon of peanut oil over high heat. Add the marinated beef in a single layer and sear without stirring for about 30 seconds, then stir-fry for another 1-2 minutes until browned.

Introduce minced garlic and ginger to the skillet, stirring for about 30 seconds until fragrant.

Return steamed broccoli to the skillet and pour the prepared sauce over the ingredients. Stir for about 1 minute until the sauce thickens.