In a bowl, combine the soy sauce, oyster sauce, cornstarch, beef broth, sesame oil, and sugar. Stir until the cornstarch is dissolved and set aside.

Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat. Add the sliced flank steak and stir-fry for about 3-4 minutes until browned. Remove the beef from the skillet and set aside.

In the same skillet, add the remaining tablespoon of vegetable oil. Add the minced garlic and ginger, and stir-fry for about 30 seconds until fragrant.

Add the broccoli florets to the skillet and stir-fry for 2-3 minutes until they are bright green and tender-crisp.

Return the cooked beef to the skillet and pour the sauce mixture over the beef and broccoli. Stir well to combine and cook for an additional 2-3 minutes until the sauce has thickened.

Serve the beef and broccoli over cooked white rice.