Combine 1 cup salsa and next 3 ingredients in a heavy-duty, zip-top plastic bag. Trim fat from steak. Add steak and peppers to bag. Seal bag, and shake until steak and peppers are well coated. Marinate in refrigerator at least 8 hours, turning bag occasionally.
Remove steak and peppers from marinade, reserving marinade. Place marinade in a small saucepan; bring to a boil. Remove from heat, and set aside.
Coat grill rack with cooking spray; place on grill over medium-hot coals (350° to 400°). Place steak, peppers, and onion on rack; brush with reserved marinade. Grill, covered, 7 minutes on each side or to desired degree of doneness.
Wrap tortillas in heavy-duty aluminum foil. Place on grill rack; grill 5 minutes or until heated.
Slice steak diagonally across grain into thin slices. Slice peppers into thin strips, and separate onion into rings. Arrange steak and vegetables evenly down centers of tortillas; sprinkle with chopped cilantro. Roll up tortillas. Top each with 1 tablespoon salsa and 1 tablespoon sour cream.