01 - Toss sliced beef with soy sauce, cornstarch, and sesame oil in a bowl. Let rest at room temperature for 10 minutes to tenderize and absorb flavor.
02 - Whisk together soy sauce, oyster sauce, brown sugar, cornstarch, and water in a small bowl until smooth. Set aside for later use.
03 - Bring a pot of water to a rolling boil. Add broccoli florets and cook for 2 minutes until bright green and just tender. Drain thoroughly and set aside.
04 - Heat 1 tablespoon vegetable oil in a large skillet or wok over high heat until smoking. Add half the beef in a single layer and sear 1 to 2 minutes until browned. Remove and repeat with remaining beef.
05 - Reduce heat to medium-high. Add remaining tablespoon of oil, garlic, and ginger. Stir-fry 30 seconds until fragrant and lightly golden.
06 - Return seared beef to the pan along with blanched broccoli. Toss vigorously to distribute evenly.
07 - Pour prepared sauce over beef and broccoli. Stir-fry 2 to 3 minutes, tossing constantly, until sauce thickens and coats everything in a glossy glaze.
08 - Transfer immediately to a serving platter. Serve hot alongside steamed rice if desired.