Cut beef Top Sirloin Steak lengthwise in half, then crosswise into 1/8-inch thick strips. Season beef with garlic powder and pepper. Set aside.
Heat 1 teaspoon oil in large nonstick skillet over medium-high heat until hot. Add onion and pepper; stir-fry 30 seconds to 1 minute. Remove from skillet; keep warm.
Heat 1/2 teaspoon oil in same skillet until hot. Add half of beef; stir-fry 2 to 3 minutes or until outside surface of beef is no longer pink. Remove from skillet; keep warm. Repeat with remaining 1/2 teaspoon oil and remaining beef.
Return beef and vegetables to skillet; cook and stir until heated through. Season with salt and pepper, as desired. Top beef with cheese slices. Heat, covered, 1 to 2 minutes or until cheese is melted; stir gently to mix. Place beef mixture on bottom half of rolls. Close sandwiches.
Nutrition information per serving: 566 Calories; 180 kcal Calories from fat; 20 g Total Fat; 8 g Saturated Fat; 7 g Monounsaturated Fat; 93 mg Cholesterol; 805 mg Sodium; 54 g Total Carbohydrate; 8.1 g Dietary Fiber; 45 g Protein; 4.4 mg Iron; 11.1 mg Niacin; 0.9 mg Vitamin B6; 2.1 mcg Vitamin B12; 8.2 mg Zinc; 83.3 mcg Selenium; 133.1 mg Choline;