Make yuzu kosho mayonnaise by adding 1 teaspoon of yuzu kosho into 2 tablespoon of mayonnaise. We’ll use this mayonnaise later.
Make the chicken marinade by mixing soy sauce with grated ginger, grated garlic, salt, and pepper. Marinade the raw chicken cutlet with this mix and let it sit for 30 minutes to an hour.
After marination, bread the chicken with corn starch, and deep fry it until golden brown.
Toast the inside of the bread slices with butter.
Assemble the sandwich by spreading yuzu kosho mayonnaise on the bread, add tomato and lettuce, chicken cutlet, and close the sandwich with another slice of bread.