Thoroughly mix all the ingredients except for the flank steak in a 1-gallon zip lock bag. Add the flank steak. Marinate in the refrigerator for at least 8 and up to 24 hours.
Preheat the grill to high or heat a skillet over high heat. Remove the flank steak from the marinade and wipe the excess liquid off with paper towels. Grill or pan sear both sides, then lower heat to medium and cook to medium rare.
Let the flanks steak rest, covered, with a clean towel for 5 to 10 minutes. Cut on the bias against the grain and serve.