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.
Heat 2 tablespoons of corn oil in a large skillet over medium to high heat. Brown the chicken breasts on both sides, about 3 minutes each side. Use tongs to turn chicken.
Remove the browned chicken, place on a plate or a small sheet pan lined with aluminum foil. Cover with aluminum foil to keep warm.
Saute sliced bell peppers and yellow onion in the same pan you cooked the chicken, over medium to low heat. Add a little more corn oil if needed as they cook. Use a wooden spoon to stir occasionally. Season with salt and black pepper to taste. Cook until softened but still a bit firm, about 8-10 minutes.
Slice the chicken into strips and place back in the cooked peppers and onions.
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.
Serve the fajitas on flour or corn tortillas and top with desired toppings such as chipotle lime crema, diced fresh tomatoes, sliced avocados, and Mexican blend shredded cheese.