Begin by slicing the boneless flank steak against the grain into 0.5 cm (1/4 inch) thick strips. In a mixing bowl, combine the beef with soy sauce, peanut oil, and cornstarch, allowing it to marinate for 10 minutes.

While the beef marinates, combine the chicken stock, Shaoxing wine, soy sauce, dark soy sauce, brown sugar, and cornstarch in a separate bowl. Whisk everything together until well mixed.

In a skillet, bring a small amount of water to a boil. Once boiling, add the broccoli florets, cover the skillet with a lid, and steam them for about 1 minute.

Heat a tablespoon of oil in the same skillet over medium-high heat. Add the marinated beef in a single layer and cook without stirring for about 30 seconds.

Once the beef is browned, flip the pieces and stir, cooking until they are nicely charred on the outside but still pink inside, about another minute.

Once the beef is cooked, stir in the minced garlic and ginger. Sauté for about 30 seconds until fragrant.

Return the steamed broccoli to the pan with the beef and pour in the prepared sauce. Stir well to combine all ingredients and allow the sauce to thicken for about 1-2 minutes.