Instructions

1. Whisk together 1/2 cup lime juice, 1/2 cup oil and 1 tablespoon of garlic and place in shallow pan or resealable plastic bags large enough to accommodate meat. Season each side of flank steak with kosher salt and place in lime marinade. Refrigerate and marinate at least 12 hours and up to 24 hours, occasionally turning.
2. In a large saute pan, heat remaining 2 tablespoons oil over medium-low heat in a large saute pan. Saute onions with a pinch of salt until just beginning to become limp. Stir in peppers and cook until peppers are tender. (If your pan is too small to accommodate peppers, cook in a separate pan with additional oil. This may be done up to 12 hours in advance, then reheated before serving.)
3. To make a guacamole, pit avocados and scoop flesh into a medium-sized bowl. Smash with a fork until creamy yet chunky and season to taste with lime juice, remaining teaspoon of garlic, kosher salt, cayenne or hot sauce and chopped cilantro to taste, reserving remaining cilantro. Refrigerate and reserve. (This may be done up to 2 hours in advance.)
4. If using tomatoes, cut into a large dice, season to taste with kosher salt and place in a bowl. Reserve at room temperature.
5. Remove flank steaks from marinade and pat dry. Rub seasoning into both sides of flank steak. Let sit at room temperature one hour. Prepare a gas or charcoal fire to high heat. Cook flank steaks until rare or medium rare, 7-10 minutes on each side. (Flank steak toughens if it is cooked past medium rare.)
6. Meanwhile, cover tortillas in foil and heat in oven or grill or reheat, on a plate covered with saran, in microwave until warm. Place shredded cheese, sour cream and remaining cilantro in small bowls.
7. Let flank steak sit at least 10 minutes on a cutting board. Slice diagonally into thin strips and place on a platter. Serve alongside tortillas, shredded cheese, sour cream, chopped cilantro, tomatoes or salsa, guacamole, sauteed onions and peppers. Let guests build their own fajita.