In a small bowl, combine 2 tablespoons soy sauce, rice vinegar, cornstarch, and sesame oil.
Add the thinly sliced beef to the marinade and toss to coat. Let it marinate for 10-15 minutes.
In a separate bowl, combine the soy sauce, oyster sauce, hoisin sauce, sugar, cornstarch, garlic, ginger, and beef broth. Stir well to combine and dissolve the cornstarch.
Heat 1 tablespoon of vegetable oil in a large skillet over medium-high heat.
Add the broccoli florets and stir-fry for 3-4 minutes, or until the broccoli is tender-crisp. Remove from the skillet and set aside.
In the same skillet, add the marinated beef in a single layer. Stir-fry for 3-4 minutes until the beef is browned and cooked through.
Return the broccoli to the skillet with the beef. Pour the stir-fry sauce over the beef and broccoli.
Stir to coat everything evenly and cook for an additional 2-3 minutes, or until the sauce thickens.
Serve the Beef and Broccoli immediately over steamed rice. Enjoy!