A classic chicken fajita recipe that is so delicious.
In large skillet, heat half of the oil over medium-high heat; cook chicken breasts, stirring often, for 5 minutes or until no longer pink inside. Transfer to plate.
Add remaining oil to pan; cook onion, garlic and chili powder for 3 minutes. Return chicken to pan. Stir in vinegar; cook for 1 minute.
Meanwhile, wrap tortillas in foil; heat in 350°F (180°C) oven for 5 minutes or until warm. Divide lettuce among tortillas; top with chicken mixture, cheese and sour cream. Roll up.