In a small bowl, stir together oil, lime juice, chili powder, garlic powder, onion powder, salt, and pepper. Pierce chicken breast all over with a fork. Place in a large Ziploc bag and pour marinade over chicken. Place in the refrigerator for at least 30 minutes to marinate.
Heat cast iron skillet on medium-high until hot. Add chicken breast and cook for 6-8 minutes per side, depending on the thickness of the chicken breast. Remove from pan and cover loosely with foil.
Add more oil to the pan, if needed, to cook the vegetables. Add onions and cook for 3-5 minutes. Add peppers and cook until desired softness. Sprinkle with salt.
Slice chicken into strips. Add back to pan with vegetables and sear for 1-2 minutes, if so desired. If chicken is still pink in the middle, make sure to cook it until it is no longer pink.
Serve with warmed tortillas, salsa, avocado, guacamole, sour cream, or any of your desired toppings. Sprinkle with fresh lime juice, if so desired.