Place peppers and onions on a sheet of foil, folding edges up slightly to form sides. Drizzle with olive oil and place on the grill, stirring occasionally.
While veggies are grilling, sprinkle taco seasoning on both sides of the chicken breasts. Allow to sit at room temperature for 15 minutes.
Add the chicken breasts to the grill. Cook about 7 minutes on each side.
Wrap tortillas in aluminum foil and put on grill.
Remove the chicken from the grill and slice into thin slices. Remove the veggies and tortilla pouch from the grill.