Slice the flank steak against the grain into thin strips, about 1/4 inch wide. Toss with soy sauce, peanut oil, and cornstarch; let marinate for 10 minutes.

Whisk together chicken or beef stock, Shaoxing wine, dark soy sauce, brown sugar, and cornstarch in a separate bowl and set aside.

Boil water in a skillet, add broccoli florets, and steam for 1 minute until bright green. Transfer to ice water, drain, and set aside.

Heat a tablespoon of peanut oil in the skillet over high heat, sear marinated beef for 3-4 minutes until browned, then add minced garlic and grated ginger, sauté for another 30 seconds.

Add cooked broccoli and prepared sauce to the skillet, stir and cook for another minute until sauce thickens.

Transfer to a serving plate with sauce over the top and serve hot with steamed jasmine rice.