With a mortar and pestle mash 3 of the garlic cloves and the salt to a paste. In a glass baking dish combine the paste, lime juice, 3 tablespoons of the oil, cumin seed, jalapenos, and pepper. Add the steak and let marinate at room temperature, turning twice, for 2 hours. The steak can be marinated and kept refrigerated, covered, overnight.
In a large skillet cook the bell peppers and onions with salt and pepper to taste in the remaining 2 tablespoons oil over moderate heat, stirring occasionally, until tender. Add the remaining garlic clove, minced, and cook, stirring, for 2 to 3 minutes. Remove from the heat and add the coriander. Toss to combine and keep warm on a platter.
Drain the steak and pat dry. Cook on a preheated grill pan for 3 to 4 minutes on each side for medium-rare meat. Transfer it to a cutting board and let it stand for 3 minutes. Cut diagonally into pieces and transfer with any accumulated juices to the platter. Wrap the steak and vegetable mixture in the tortillas and serve with salsa and guacamole.
Recipe courtesy of Gourmet Magazine