In a ziplock bag combine chicken and Italian dressing and let sit while you prep the other items
Place chicken, marinade and chili powder into a skillet and saute until chicken is cooked through. Transfer chicken to another dish and cover to keep warm.
Add onions to the pan and saute for about 5 mins. Add peppers and cook for another 5-7 mins
Add chicken back into the pan and saute until heated through
Spoon the chicken and veggies into tortillas and roll up