In a large bowl, combine 2 tablespoons oil, lemon juice, 2 tablespoons Hidden Valley® Original Ranch® Seasoning & Salad Dressing Mix Shaker and other seasonings; add the chicken. Turn to coat; cover. Refrigerate 1-4 hours. , In a large cast-iron or other heavy skillet, saute peppers and onions in remaining oil until crisp-tender. Remove and keep warm. , Drain chicken, discarding marinade. In the same skillet, cook chicken over medium-high heat until no longer pink, 5-6 minutes. Return pepper mixture to pan; heat through. , Spoon filling down the center of tortillas; fold in half. In a small bowl, stir together sour cream and remaining 1 tablespoon Hidden Valley® Original Ranch® Seasoning & Salad Dressing Mix Shaker . Serve with fajitas and, if desired, additional toppings.