Combine the beef, 2 teaspoons of corn starch, soy sauce, sugar, olive oil, pepper, and rice wine vinegar in a bowl. Coat the beef with all the ingredients in the marinade. Marinate for 30 minutes or overnight. For the best flavor, marinate overnight.
Blanche the broccoli. Bring a pot of water to a boil. Add the broccoli and cook for 1-2 minutes until it turns a vibrant green color. Take it out and set aside.
Heat a tablespoon of oil over high heat. Add the garlic, ginger, and marinated beef. Cook for 1-2 minutes until the beef is brown on all sides.
Add the broccoli, oyster sauce, and sesame oil (cook for 30 seconds).
Mix together 1 tbsp of corn starch and 1 tbsp of water. Add to the pan. Mix and cook for another 30 seconds.
Taste the dish for seasoning. Add some salt if it tastes bland. Add some sugar if you want it a bit sweeter.
Serve with white rice or your grain of choice.