In a bowl, combine flour, garlic powder, and black pepper. Pat steak pieces dry with paper towels, then dredge in flour mixture. Make sure both sides are evenly coated, then shake off excess.
Heat oil in a skillet under medium-high heat until hot. Brown steak pieces on both sides, about 3-4 minutes a side. Add onions and peppers and cook until onions are tender, about 5 minutes.
Add stewed tomatoes and simmer, uncovered for 15-20 minutes or until steak is cooked through. Serve with hot noodles, rice, or mashed potatoes. Enjoy!