Combine marinade ingredients in small bowl; mix well. Place beef Flank 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.
Remove steak from marinade; discard marinade. Place steak on grid over medium, ash-covered coals. Grill, covered, 11 to 16 minutes (over medium heat on preheated gas grill, 16 to 21 minutes) for medium rare (145°F) to medium (160°F) doneness, turning occasionally. Carve steak across the grain into thin slices. Season with salt, as desired.
Nutrition information per serving: 167 Calories; 54 kcal Calories from fat; 6 g Total Fat; 3 g Saturated Fat; 2 g Monounsaturated Fat; 66 mg Cholesterol; 71 mg Sodium; 2 g Total Carbohydrate; 0.2 g Dietary Fiber; 24 g Protein; 1.5 mg Iron; 9.4 mg Niacin; 0.5 mg Vitamin B6; 1.4 mcg Vitamin B12; 4.3 mg Zinc; 27.2 mcg Selenium; 90.8 mg Choline;