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

Make the sauce by whisking together soy sauce, oyster sauce, sesame oil, cornstarch mixture, and black pepper until smooth.

Heat your pan on medium-high until smoking hot.

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

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

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