Marinate chicken: pound chicken to an even thickness (about 1-inch thick), then cut in half horizontally to make two thinner breasts. I used two (8-oz.) breasts that I cut in half to get four (4-oz.) pieces. Add chicken to a large bowl or ziploc bag with the pickle juice. Cover and refrigerate for 30 minutes. Then discard the marinade and pat the chicken dry with a paper towel. Season both sides generously with salt and pepper.
Extra crispy step: preheat oven to 400F. Add panko breadcrumbs to a large baking sheet. Spread out in an even layer and lightly spray with cooking spray. Bake for 3-4 minutes, then shake breadcrumbs around and bake for another 3-4 minutes, or until breadcrumbs are golden brown.
Prepare breading station: get three shallow bowls. In one, mix together the flour, confectioners sugar and all the seasonings. In the next, whisk together the eggs and mustard. Finally in the last bowl, add the Panko.
Bread the chicken: first, dip the chicken in the flour mixture. Then dip in the egg mixture, letting any excess drip down. Finally, dip the chicken completely in the Panko. Press down with your fingers to help it stay on. Coat all sides and shake any excess off. Repeat with all the chicken.
Cook chicken: preheat air fryer to 375F. When ready, spray the air fryer basket with cooking spray. Place the chicken in the air fryer basket and spray the top with cooking spray (from a distance). Cook for 5 minutes. Spray the top of the chicken again, then carefully flip the chicken, spray the new top of the chicken and cook for another 5 minutes or until internal temperature reaches 155F*. Transfer chicken to a paper-towel lined plate and repeat with the remaining chicken.
Assemble chicken sandwich: add mayo to each side (about 3/4 tablespoon to each bun half). Add the mustard to the top bun (if using), then top the bottom bun with the pickles, chicken, coleslaw and freshly cracked black pepper. Top with the top bun and ENJOY!