Hot and Tangy Broccoli Beef

It has been a while since I have shared a recipe. I am not sure where I got this recipe so wanted to let everyone know this isn't my recipe. I did make it my own. So here is the recipe.
 1-2 pounds boneless beef cut into thin strips.
1 tablespoon cornstarch
5 tablespoons soy sauce, divided
1 heaping teaspoon of minced garlic
1/2 teaspoon sugar
roughly 1 pound of fresh broccoli flowerets
4 teaspoons cornstarch
crushed red pepper flakes
vegetable oil
1 medium onion, thinly sliced
2 teaspoons rice vinegar

Combine the meat with 1 tablespoon of cornstarch, 3 tablespoons of soy sauce, sugar, and garlic in a bowl, stir and let stand for about 10 minutes.
Meanwhile prepare flowerets into bite-size pieces.
Combine 1 cup water, remaining soy sauce, 4 teaspoons cornstarch and crushed red pepper flakes in a small bowl. Set Aside.
Heat about 1 tablespoon of oil in a large skillet over medium to high heat. Add beef and stir-fry until it is the way you like it. Remove from pan.
Heat about another 2 tablespoons of oil in the same pan that you cooked the beef. Add broccoli and onion; stir-fry for about 2 minutes. Sprinkle about 1 tablespoon of water over the vegetables; cover and cook until the vegetables are the way you like them. Stir occasionally.
Add beef and the soy sauce mixture; cook and stir until sauce boils and thickens. Remove from heat; stir in rice vinegar.
I serve this over rice.
You could use chicken or pork instead of the beef and you can also add other vegetables if you like. You can also omit the red pepper flakes if you want but we like our a little spicy.
Hope this gives you something to think about and try. I know I am always looking for any new ideas for dinner.
Until next time enjoy your day.