Set a jumbo zip lock bag in a large glass measuring cup. Combine all the ingredients in the plastic bag. Score the flank steak and place in the bag. Seal the bag and chill. Marinate at least 20 minutes and up to overnight.
Heat a grill or grill pan. Remove the flank steak from the bag and pat dry. Grill 4 to 5 minutes per side. Let rest 5 to 10 minutes before carving.
Courtesy of Ann Volkwein