Combine thyme, garlic and pepper; press evenly onto beef Flat Iron Steak.
Place steak on grid over medium, ash-covered coals. Grill, covered, 10 to 14 minutes (over medium heat on preheated gas grill, 12 to 16 minutes) for medium rare (145°F) to medium (160°F) doneness, turning occasionally. During last 2 minutes of grilling, sprinkle with cheese. Carve steak across the grain into thin slices; season with salt and pepper, as desired.
Nutrition information per serving: 200 Calories; 108 kcal Calories from fat; 12 g Total Fat; 5 g Saturated Fat; 0 g Trans Fat; 0.5 g Polyunsaturated Fat; 4.8 g Monounsaturated Fat; 70 mg Cholesterol; 110 mg Sodium; 1 g Total Carbohydrate; 0 g Dietary Fiber; 22 g Protein; 3 mg Iron; 287.7 mg Potassium; 5.9 mg Niacin; 0.4 mg Vitamin B6; 5 mcg Vitamin B12; 7.8 mg Zinc; 33 mcg Selenium; 91.6 mg Choline;