Mix soy sauce, lime juice, and cilantro and pour over meat. Marinate for at least 15 minutes but up to several hours. Discard leftover marinade. Over medium high heat, sauté peppers, onions and garlic into a large skillet in corn oil for 2 to 3 minutes. Pour teriyaki sauce evenly over vegetables; toss to combine. Remove from heat, cover and serve with meat and tortillas.
Set grill grids at low position. Preheat grill to high. Heat tortillas on grill warming rack. Stack tortillas and wrap in aluminum foil to hold in heat. Grill meat 3 to 5 minutes on each side until degree of doneness is achieved. Cut steak into slices 1/8 to 1/4 inch thick and 4 to 5 inches long.
To assemble fajitas, place 2 or 3 strips of meat onto tortilla, add peppers, onions, shredded cheese, and sour cream. Wrap tortilla.
