Grilled Beef Fajitas

5 pounds Western griller or shoulder London broil, 3/4 inch thick4 teaspoons salt2 1/4 teaspoons freshly ground black pepper1 1/2 cups lime juice3 tablespoons minced garlic 3/4 cup minced yellow onion2 tablespoons olive oil2 red bell peppers, seeded and cut into thin strips2 green bell peppers, seeded and cut into thin strips2 yellow bell peppers, seeded and cut into thin strips 1/2 red onion, sliced16 corn or flour tortillas, 6 inches in diameterTrim the meat to remove any visible fat. In a medium bowl, combine the salt, pepper, lime juice, garlic and minced onion. Transfer to a baking dish. Add the beef, cover and refrigerate. Marinate for at least 2 hours and up to 24 hours.When ready to cook, preheat a gas grill to high. If you are using a charcoal grill, build a fire and let it burn down until the coals are glowing red with a light coating of white ash. Spread the coals evenly. Clean the cooking grate.Grill the steaks for 7 to 8 minutes per side for medium doneness. Remove the steaks from the grill and allow them to cool, about 5 minutes. Cut the steaks into 1/4-inch-thick strips, being sure to cut across the grain, and on a slight bias. Set aside.In a large saute pan, heat the olive oil over medium heat. Saute the peppers and onions for 5 to 7 minutes, or until they just begin to soften. Add the steak and cook until just heated through, about another 2 to 3 minutes.Meanwhile, grill or toast the tortillas until softened and warm, about 20 seconds per side.Serve the steak mixture with the tortillas and a variety of toppings, such as cheese, sour cream, guacamole or salsa.Serves eight.Adapted from "Grilling" by the Culinary Institute of America. (2006 Lebhar-Friedman)