01 - Toss the sliced beef with 1 tbsp cornstarch, 1 tbsp soy sauce, and 1 tsp sesame oil in a bowl. Set aside to marinate while preparing other ingredients.
02 - Whisk together 1/4 cup soy sauce, oyster sauce, brown sugar, 1 tbsp cornstarch, and water in a small bowl. Set aside.
03 - Bring a pot of water to a boil. Blanch broccoli for 1 minute, then drain and rinse under cold water to stop cooking. Set aside.
04 - Heat 1 tbsp vegetable oil in a large skillet or wok over high heat. Add the beef in a single layer. Sear for 1-2 minutes until just browned. Remove to a plate.
05 - Add the remaining 1 tbsp oil to the pan. Sauté garlic and ginger for 30 seconds until fragrant.
06 - Add broccoli and stir-fry for 2 minutes. Return the beef to the pan. Pour in the soy sauce glaze. Stir constantly until the sauce thickens and everything is well coated, about 2-3 minutes.
07 - Remove from heat. Garnish with sesame seeds and green onions if desired. Serve hot with steamed rice.