Found this one online a few years back. This isn't my recipe, but it's a great way to grill a flank! The mango and cider vinegar team up to tenderize the meat, so Levins suggests marinating for no more than 6 hours. John Levins' grilled tropical marinated flank steak 1 ripe mango, peeled and pitted 4 garlic cloves 3 shallots, peeled 2 jalapeno peppers, stemmed 1 cup orange juice 1/2 cup apple cider vinegar 1/2 cup olive oil 1 1/2 teaspoons chopped fresh rosemary 1 1/2 teaspoons chopped fresh sage 1 teaspoon salt 1 (roughly 2 lb) flank steak Pulse the mango in a food processor fitted with a metal blade until it is pureed. Add the garlic, shallots, and jalapenos, and pulse until minced. Add the orange juice, vinegar, oil, rosemary, sage, and salt, and pulse to blend. Place the flank steak in a large nonreactive container. Cover completely with the marinade and seal the container. Refrigerate for 4 hours but no more than 6 hours. Prepare the grill. When the coals are gray (or the flame is adjusted to medium), remove the meat from the marinade, place on the grill, and save the marinade. Grill the steak for 5 to 7 minutes on each side (for medium-rare), or until cooked to desired doneness. Place the marinade in a small saucepan and boil for 5 minutes. Transfer the meat to a cutting board and cut on the bias across the grain into thin slices (since flank fibers are pretty tough even after tenderizing). Spoon the warm marinade over the sliced steak. Serves 6.