Prepare your ingredients: Slice flank steak and chop broccoli into uniform florets. Mince garlic finely.

Make the sauce: In a small bowl, whisk together soy sauce, oyster sauce, sesame oil, cornstarch mixture, and black pepper until smooth.

Heat your pan: Use a skillet or wok heated over medium-high until smoking hot.

Cook the beef: Add sliced steak in a single layer; sear for about 2 minutes before stirring. Cook for a total of about 4 minutes until just browned.

Add vegetables: Toss in broccoli florets and minced garlic. Stir-fry for another 2–3 minutes until broccoli is vibrant green and tender-crisp.

Combine: Return beef to the pan, pour in the sauce, and stir over high heat until bubbling and thickened. Serve immediately with rice or noodles.