Place the ground beef in a large skillet or wok, season with salt and pepper, a tsp of minced garlic. Cook over medium high heat until cooked through crumbling into medium size chunks until it is cooked through and no longer pink.
Remove the ground beef from pan drain the ground beef if necessary. (If you use lean ground beef you should not have to drain it)
Place the sliced onion in the skillet with some of the ground beef fat and saute for about 5 minutes over medium-high heat or until they are translucent.
Add in the rest of the chopped veggies and stir. Continue cooking over medium heat for about 5- 10 minutes or until the veggies are softened.
While the vegetables are cooking whisk together the beef broth, soy sauce, corn starch, sesame oil, brown sugar, rice wine vinegar, ginger and garlic in a medium size bowl.
Add the ground beef back into the skillet
Pour the sauce mixture over the vegetables and ground beef and stir well. Continue to cook over medium-high heat for about 3-4 minutes. The sauce will thicken as it cooks.
Serve warm over rice or noodles garnished with sesame seeds if desired.