Slice flank steak thinly against the grain and place it in a mixing bowl. Add soy sauce, peanut oil, and cornstarch, ensuring the meat is evenly coated. Allow it to marinate for at least 10 minutes at room temperature.

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

Set a pan over medium heat and add a splash of water. Once it starts to simmer, add the broccoli florets and cover the pan. Steam for about 1 minute, until bright green and tender-crisp.

In the same pan, heat a tablespoon of peanut oil over medium-high heat. Spread the marinated flank steak in a single layer. Allow it to sear without moving for 30 seconds, then flip and cook for another 30 seconds.

Stir in the minced garlic and ginger into the cooked beef. Cook for about 30 seconds, stirring constantly until the garlic is golden and aromatic.

Return the steamed broccoli to the pan with the beef and pour the prepared sauce over the top. Gently stir everything together for about 1 minute over medium heat, until the sauce thickens.