Combine marinade ingredients in small bowl; mix well. 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.
Remove steak from marinade; discard marinade. Place steak on grid over medium, ash-covered coals. Grill flank steak, covered, 11 to 16 minutes for medium rare to medium doneness (top round steak 12 to 14 minutes for medium rare doneness; do not overcook), turning occasionally. Carve steak across the grain into thin slices. Season with salt, as desired.
Cook’s Tip: To broil, place steak on rack in broiler pan so surface of beef is 2 to 3 inches from heat. Broil flank steak 13 to 18 minutes for medium rare to medium doneness (top round steak 17 to 18 minutes for medium rare doneness; do not overcook), turning once. One and three-fourths pounds beef top round steak, cut 1 inch thick, may be substituted for flank steak. For charcoal, grill, covered, 12 to 14 minutes (for gas, grill, covered, 16 to 19 minutes) for medium rare (145F) to medium (160F) doneness, turning occasionally.
For more information on why meat needs to rest after cooking, watch this video for tips from the “Butcher Boys” of Porter Road Butcher in Nashville, TN