Combine salsa, lime peel and juice, and cumin in small bowl. Place beef Steak in food-safe plastic bag. Pour 3/4 cup salsa marinade over steak; turn steak to coat. Close bag securely and marinate in refrigerator 6 hours or overnight. Cover and reserve remaining marinade in refrigerator for sauce.
Remove steak from marinade; discard marinade. Place steak on grid over medium, ash-covered coals. Grill 3/4-inch thick steak, covered, 10 to 11 minutes (over medium heat on preheated gas grill, times remain the same) for medium rare (145°F) doneness, turning occasionally. (Do not overcook). Place 1-inch steak on grid over medium, ash-covered coals. Grill, covered, 12 to 14 minutes (over medium heat on preheated gas grill, 16 to 19 minutes) for medium rare (145°F) doneness, turning occasionally. (Do not overcook.)
Meanwhile stir 3 tablespoons cilantro into reserved marinade. Carve steak into thin slices. Serve with sauce and tortillas, if desired. Garnish with cilantro, if desired.
Nutrition information per serving: 190 Calories; 45 kcal Calories from fat; 5 g Total Fat; 2 g Saturated Fat; 2 g Monounsaturated Fat; 61 mg Cholesterol; 698 mg Sodium; 7 g Total Carbohydrate; 2.5 g Dietary Fiber; 27 g Protein; 2.4 mg Iron; 5 mg Niacin; 0.4 mg Vitamin B6; 1.5 mcg Vitamin B12; 4.8 mg Zinc; 32.8 mcg Selenium;