1 beef Flank Steak (about 1-1/2 to 2 pounds)
1 cup light balsamic vinaigrette dressing, divided
1 tablespoon unsweetened cocoa powder
1 tablespoon ground espresso coffee
1/2 teaspoon ground black pepper
1 medium onion, chopped
Combine 1/3 cup vinaigrette, cocoa, coffee and pepper in small bowl. Place beef steak and marinade in food-safe plastic bag; turn steak to coat. Close bag securely and marinate in refrigerator 6 hours or as long as overnight, turning occasionally.
Remove steak from bag; discard marinade. Place steak on rack of broiler pan so surface of beef is 2 to 3 inches from heat. Broil 13 to 18 minutes for medium rare (145°F) to medium (160°F) doneness, turning once.
Meanwhile, cook onion and remaining 2/3 cup balsamic vinaigrette in medium saucepan over medium heat, uncovered, 8 to 10 minutes or until onion is tender. Remove from heat.
Carve steak diagonally across the grain into thin slices. Top with onion slices.
Nutrition information per serving: 190 calories; 8 g fat (3 g saturated fat; 3 g monounsaturated fat); 66 mg cholesterol; 457 mg sodium; 9 g carbohydrate; 1 g fiber; 24 g protein; 6.9 mg niacin; 0.5 mg vitamin B6; 1.4 mcg vitamin B12; 1.7 mg iron; 27.4 mcg selenium; 4.4 mg zinc; 91.76 mg choline.