Place peppers and onion slices on grid over medium, ash-covered coals (over medium heat on preheated gas grill). Grill, covered, 15 to 20 minutes or until onion is tender and pepper skins are blackened, turning occasionally. Place peppers in food-safe plastic bag; close bag. Set peppers and onion aside.
Meanwhile combine garlic and cumin; press evenly onto beef steaks. Place steaks on grid over medium, ash-covered coals. Grill, covered, 7 to 11 minutes (over medium heat on preheated gas grill, covered, 8 to 13 minutes) for medium rare (145°F) to medium (160°F) doneness, turning occasionally. Remove; keep warm.
Remove and discard skins, stems and seeds from peppers when cool enough to handle. Chop peppers and onion. Combine chopped vegetables, mango, chopped cilantro, lime juice and salt in medium bowl. Set aside.
Place tortillas on grid. Grill, uncovered, 30 seconds on each side or until heated through and lightly browned.
Carve steaks into slices. Season with additional salt, as desired. Top tortillas with equal amounts of beef and mango salsa. Garnish with cilantro sprigs and lime wedges, if desired.
Nutrition information per serving: 370 Calories; 126 kcal Calories from fat; 14 g Total Fat; 4.5 g Saturated Fat; 0.5 g Trans Fat; 0.5 g Polyunsaturated Fat; 6.2 g Monounsaturated Fat; 70 mg Cholesterol; 210 mg Sodium; 37 g Total Carbohydrate; 3 g Dietary Fiber; 26 g Protein; 3 mg Iron; 541.4 mg Potassium; 8.5 mg Niacin; 0.5 mg Vitamin B6; 2.4 mcg Vitamin B12; 8.9 mg Zinc; 30.7 mcg Selenium; 10.1 mg Choline;