Season steak with salt & pepper. Toss with cornstarch and set aside while you prepare the vegetables
Place1 tablespoon of oil in a pan or wok. Cook the beef in 2 small batches over medium high until browned, about 2-3 minutes (beef does not need to be cooked through). Remove from pan and set aside. Add vegetables to the pan and cook about until tender crisp, 4-5 minutes. Remove from pan and set aside with the beef.
Combine sauce ingredients except corn starch in a bowl and stir well.
Turn the heat up to medium-high and add the sauce. Bring to a simmer. Combine cornstarch with 3 tablespoons water (or broth) and add it the sauce a little bit at a time while whisking to reach desired consistency. Let simmer 2minutes. Add vegetables, beef (and any juices) to the pan and cook until heated through.
Serve with noodles or with rice
