In a large bowl, whisk together 1 tablespoon of oil, lime juice, chili powder, cumin, salt, and garlic powder. Add the chicken to the bowl and gently toss the chicken in the marinade. Set the bowl aside so the chicken can marinate for about 10 minutes. Alternatively, you can place the chicken and marinade in a baggie or a container (with a lid) and let it rest in the fridge overnight or all day until you’re ready to make the fajitas.
Warm a large skillet over high heat. Once hot, add the marinated chicken. Sauté until the chicken is cooked through, or about 7 minutes. Remove the chicken from the skillet, and set aside.
Add 1 tablespoon of oil to the skillet. Add the peppers and onions. Sprinkle the veggies with a pinch of salt to bring out their sweetness. Saute the veggies until they are soft and the onions are translucent, about 10 minutes.
Add the chicken back to the skillet, stirring to combine the chicken and veggies. Saute for another 5 minutes, or until the chicken and veggies are combined and heated through.
Serve the fajita filling over warm corn tortillas (or rice or lettuce), with any additional serving options desired.