Place the flank steak in a large, plastic resealable bag. In a 2-cup measuring cup combine the remaining ingredients. Pour the marinade mixture into the bag with the steak, seal and marinate in the refrigerator at least 4 hours and up to 12 hours in advance.
Preheat a gas or charcoal grill. Remove the steak from the marinade. Pour the marinade into a small saucepan and bring to a boil. Lower the heat to medium-low and simmer the marinade for 10 minutes. Remove saucepan from the heat and keep warm. Place the steak on the grill and cook to desired doneness, about 6 minutes per side for rare. Transfer the steak to plate and let stand for 5 minutes before carving. Cut the steak across the grain into thin diagonal slices, and serve with the marinade sauce.
Essence (Emeril's Creole Seasoning):
Yield:about 2/3 cup
Combine all ingredients thoroughly and store in an airtight jar or container.
Recipe from "New New Orleans Cooking", by Emeril Lagasse and Jessie Tirsch. Published by William and Morrow, 1993.