In a large Ziploc bag add the marinade ingredients and push around on the outside of the bag with your fingers to combine.
Lightly flatten the chicken by placing one piece at a time inside a plastic bag or between two pieces of plastic wrap. Use a wooden rolling pin or a meat tenderizer to flatten the chicken slightly and make it even thickness.
Place each piece of flattened chicken into the marinade. Place in the refrigerator for 2 hours and up to 24 hours.
Make the chipotle lime crema by stirring together the sour cream, mayonnaise, lime juice, pinch of salt, and chopped cilantro. Cover with plastic wrap and place in the refrigerator until ready to serve the fajitas.