Mince the garlic. Chop broccoli and onion. Slice beef into thin strips
In a small glass bowl add water, soy sauce, rice vinegar, sugar, ginger, and pepper. Mix.
Brown the beef in a pan until done, 3-6 minutes. Set aside and wipe down the pan.
Add sesame oil to the pan along with onion, garlic, and broccoli. Let cook for 5 minutes
Add the beef and sauce mix to the pan. Cook for 2-3 minutes, until the beef is heated through and the sauce thickens. If the sauce is too watery, add half a teaspoon of cornstarch to thicken it.
Serve topped with green scallions, toasted sesame seeds, and rice or a green salad.