In a medium-sized bowl, mix the juice of 1 lime, 2 tablespoons of olive oil, 2 cloves of minced garlic, ? teaspoon cumin, ? chopped jalapeno pepper, and ? cup minced cilantro. Place 1 ? pounds sirloin steak strips into this mixture and use your hands to rub the mixture into the steak. Cover the steak with plastic wrap, and put it in the refrigerator for about 4 hours to marinate. (If you do not have this amount of time, you may continue with the recipe.) Add 1 package fajita seasoning mix to the marinated steak and blend thoroughly. Heat 2 tablespoons olive oil in a large, deep skillet. When hot, add all of the steak pieces and stir-fry until done. If the mixture becomes thick, you can add water to thin it to your desired consistency. The steak will cook very quickly?about 6 to 8 minutes. When the steak is done, remove it from the skillet, and place it on a serving platter. Cover with aluminum foil to keep it hot while you prepare the remainder of your dinner. Place the wedges from 1 onion, 1 green pepper, and 1 red pepper into the skillet that was used to brown the steak. Saute the vegetables until clear and beginning to brown. Remove them from the skillet, and place them on their serving platter. Place your flour tortillas on a serving platter and microwave them for a very short amount of time to soften them. To serve a fajita, take one warm flour tortilla and place some browned steak strips in a line near the bottom. Place sauteed vegetables over the steak, and then sprinkle shredded Cheddar cheese over the vegetables. Fold the bottom edge of tortilla over the meat, vegetable, and cheese, and tuck in both sides. Roll the tortilla all the way up and place on a serving plate. Accompany a couple of fajitas with my Precocious Pico de Gallo, my South of the Border Guacamole, some sour cream, and a refreshing glass of limeade to drink! Enjoy!