Slice flank steak against the grain into thin strips. Marinate with soy sauce, peanut oil, and cornstarch for 10 minutes.

Mix chicken stock, Shaoxing wine, both soy sauces, brown sugar, and cornstarch until smooth to make the sauce.

Steam the broccoli in boiling water for 1 minute until bright green and tender-crisp, then set aside.

Heat peanut oil in a skillet over medium-high heat and sear marinated beef for 2-3 minutes until lightly browned.

Push beef to the side, add minced garlic and ginger, and stir-fry for 30 seconds.

Add steamed broccoli and pour in the sauce, cooking for another minute while stirring until the sauce thickens.