Rinse the chicken and pat dry with a paper towel. Slice the chicken diagonally. This cutting technique is called “Sogigiri” in Japanese. Each piece will have more surface area so it will cook faster. Tip: The Japanese use chopsticks to eat Chicken Katsu, so the chicken is cut into bite-sized pieces.
Put the chicken in a bowl and add sake, salt, and pepper. Set aside for 15 minutes.
Dust the flour on the chicken and remove the excess.
Then dip each chicken piece in the beaten egg.
Lastly, dredge the chicken in panko and remove the excess. If you have time, let the chicken sit in the refrigerator for 15 minutes.
Heat 1/2 inch of oil in the cast iron skillet (you can use a heavy-bottomed Dutch oven). Drop a piece of panko to see if the oil is ready. If you are new to deep-frying, use a thermometer to check the temperature of oil (Read How To Deep Fry Food). The oil for Chicken Katsu should be 350 ºF (180 ºC) degree.
Put 2-3 pieces of chicken in at a time. If you put too many chicken pieces, the temperature of the oil will drop too quickly and the chicken will end up absorbing too much oil.
Deep fry until both sides are golden brown, about 5-6 minutes. Then transfer to a wire rack or paper towel-lined tray to remove excess oil.
Between batches, make sure to pick up breadcrumbs. When you don’t pick them up, the breadcrumbs will get burnt and the oil will get darker. Make sure to keep the oil clean throughout deep frying.