1Combine the chicken, lime juice and zest, fajita seasoning, garlic, and cilantro into a big resealable bag and refrigerate for about 3-4 hours at the most.
2Over medium-medium high heat, cook chicken in a cast iron or stainless steel pan with a little oil. When cooked through with nice color on both sides, remove from skillet and let rest.
3In the same skillet, add onions and peppers. Saute until the veggies cooked but are still a little firm. Add the chicken (sliced) to the veggies and serve on warm tortillas with cheese and sour cream.