Pat the pickles dry with a paper towel, absorbing as much liquid as possible. Chop the pickles finely. In a bowl, combine the chopped pickles, hot sauce, garlic powder, and mayonnaise. Let sit in the fridge until ready to serve.
Set up three bowls for dredging your chicken. In one bowl combine the flour, cayenne pepper, salt, and garlic powder. In the next bowl, combine the egg and ¼ cup of hot sauce. In the third bowl, add the panko bread crumbs.
Prep your chicken by placing the chicken in between two pieces of plastic wrap and pounding it thin with either a mallet or a skillet.
Dredge all of your chicken slices by placing them first in the flour mixture, second in the egg mixture, and third in the breadcrumbs mixture.
Heat olive oil in your frying pan on medium-high heat. It should reach a temperature in between 320 and 370 degrees Fahrenheit to fry. Shallow fry the chicken on each side for about 3-4 minutes and until golden brown. Chicken is cooked when it reaches an internal temp of 165 degrees Fahrenheit.
Let the chicken rest for a minute or two on paper towels or a baking rack to let the excess oil drain.
To serve, spread the mayo and pickle mixture on both sides of the bread and cover one side with shredded or chopped lettuce. Place the still hot chicken katsu on the lettuce and top with the second piece of bread. Cut the sandwich in half for easy eating and enjoy!