Take a large piece of cling wrap. Place a chicken on one side and fold over the other half. If you have a very large of cling wrap, you can place more chicken pieces.
Pound the chicken until the meat is half an inch to three-quarters inch in thickness. It is important for the thickness to be uniform for even cooking. And the chicken meat shouldn’t be too thick to avoid a raw center and a burnt coating.
Lay the chicken pieces flat and sprinkle with salt and freshly ground black pepper.
Place the flour, beaten egg and panko in three shallow bowls.
Dredge each chicken thigh in flour; shake off the excess.
Dip each floured chicken thigh in the beaten egg, making sure that every inch of the surface is coated with egg.
Roll each chicken thigh in panko. Make sure that the panko coating is even.
Heat enough cooking oil so that it is at least two inches deep. The ideal frying temperature is 145F to avoid burnt breading and raw meat.
If the chicken fillets are not completely submerged in oil, check the underside after about three minutes. When the underside is golden brown, flip the chicken thighs over to brown the opposite side.
Cut the chicken katsu into bite-size pieces. Arrange over rice. Spoon over some of the sauce. Serve with vegetables on the side. Sprinkle with finely sliced scallions for garnish.