Spray a large skillet with vegetable cooking spray, and over high heat, quickly sear flank steak. Remove to a cutting board.
In the skillet combine thinly sliced onion, chopped tomatoes, water, and chili powder. Simmer uncovered for 5 minutes.
Slice the steak and return to the skillet and cook until done, about 5 minutes. Season with garlic salt, and pepper.
Servings: 4