Remove chicken from Ziploc bag and discard remaining marinade. Toss bell peppers and onion with a small amount of canola oil. Add your desired amount of salt and pepper. Cook chicken until no longer pink. Remove from pan and keep warm. Cook peppers and onions until they are crisp-tender.
Warm tortillas according to package directions. Serve with optional sour cream, lime wedges, avocado slices or guacamole.