Begin by marinating the beef. In a bowl, combine the sliced beef with 1 tablespoon of soy sauce and a sprinkle of salt and pepper. Let it sit while you prepare the other ingredients.
In a small bowl, mix the soy sauce, oyster sauce, cornstarch, water, sesame oil, and sugar together to make the sauce. Set this mixture aside.
Heat 2 tablespoons of vegetable oil in a wok or large skillet over medium-high heat.
Once the oil is hot, add the marinated beef, cooking for about 3-4 minutes until browned. Remove the beef from the pan and set aside.
In the same pan, add 1 tablespoon of oil if needed, then toss in the minced garlic and ginger. Sauté for about 30 seconds until fragrant.
Add the broccoli florets to the pan and stir-fry for 2-3 minutes until they are bright green and tender-crisp.
Return the cooked beef to the pan with the broccoli. Pour the sauce over the mixture and stir everything together until well combined. Cook for an additional 2 minutes until the sauce thickens slightly.
Serve hot over cooked rice or noodles.