1Slice the bottom round steak into thin strips.
Cut the yellow onion, red bell pepper, yellow bell pepper, orange bell pepper, and green bell pepper into thin strips.
In a small bowl, mix together the soy sauce, rice vinegar, worcestershire sauce, brown sugar, mustard, onion powder, garlic powder, and steak seasoning.
Heat a large skillet or wok over medium-high heat.
Add the steak strips to the skillet and cook until browned, about 3-4 minutes.
Remove the steak from the skillet and set aside.
In the same skillet, add the sliced onions and bell peppers. Stir-fry for about 5-7 minutes until they are tender-crisp.
Return the steak to the skillet and pour the sauce mixture over the steak and vegetables.
Stir well to coat everything evenly with the sauce.
Cook for an additional 2-3 minutes until the sauce has thickened slightly.
Serve hot over rice or noodles if desired.