In a large bowl, combine 2 tablespoons oil, lemon juice and seasonings; add the chicken. Turn to coat; cover. Refrigerate for 1-4 hours.
While chicken is marinating, prepare and cut your peppers and onions.
In a large cast-iron or other heavy skillet, saut 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. Serve with desired toppings.
