01 - Toss sliced beef with 2 tbsp soy sauce, 1 tbsp cornstarch, and sesame oil. Let marinate for 10 minutes.
02 - Whisk together 4 tbsp soy sauce, oyster sauce, brown sugar, 1 tbsp cornstarch, and water. Set aside.
03 - Bring a pot of water to a boil. Blanch broccoli florets for 2 minutes, then drain and set aside.
04 - Heat 1 tbsp vegetable oil in a large skillet or wok over high heat. Add half the beef in a single layer, sear for 1–2 minutes until browned, then remove. Repeat with remaining beef.
05 - Lower heat to medium-high, add remaining 1 tbsp oil, garlic, and ginger. Stir-fry for 30 seconds until fragrant.
06 - Return beef to the pan, add broccoli, and toss well. Pour in the sauce and stir-fry for 2–3 minutes until sauce thickens and everything is evenly coated. Serve hot with steamed rice if desired.