Ingredients

For the Tonkatsu Sauce
1/4 cup ketchup
1 tablespoon Worcestershire sauce
1/2 tablespoon low-sodium soy sauce
1/2 tablespoon mirin
1/2 tablespoon granulated sugar
1 teaspoon brown sugar
1/4 teaspoon garlic powder
1/8 teaspoon ground ginger

For the Chicken
4 boneless skinless chicken thighs (5 ounces each) – see note below to use chicken breasts
1/2 teaspoon coarse salt
1/4 teaspoon freshly ground black pepper
1 large egg
1/2 tablespoon vegetable oil
1/4 cup all-purpose flour
1 1/3 cup panko Japanese breadcrumbs
3 cups vegetable oil , for deep frying

For Serving
katsu sauce
cooked sticky white sushi rice
shredded cabbage salad
macaroni salad
sliced tomato

Instructions

Make the katsu sauce by whisking all the ingredients together in a small bowl. Taste and adjust the sauce according to your liking. Set aside.
Trim any excess skin, fat, or gristle off of each chicken thigh, then place between some plastic wrap and tenderize the meat, gently pounding until both sides are flattened and about a 1/2-inch even thickness.
Sprinkle the salt and pepper evenly over the surface of each side of the chicken pieces.
Set up a breading station with 3 shallow bowls: one with the flour, one with the egg, and one with the panko breadcrumbs. (Beat the egg with the 1/2 tablespoon vegetable oil.)
Dredge the chicken with a thin coating of flour, making sure not to miss any spots, shaking off any excess. Then coat it in the beaten egg, making sure there is no dry flour left, letting any excess dip off. And finally coat the chicken in the panko fully, gently pressing the panko into the cutlet to adhere.
Add the oil to a medium-size, heavy-bottomed pot – the oil should be 1 & 1/2 inches deep. (If you use a larger pot, you will need to add more oil to get it 1 & 1/2 inches deep.) Start heating the oil to 340F over medium heat.
Once oil has reached 340F, gently lower one piece of chicken at a time into the hot oil and deep-fry for 3 to 4 minutes on each side, until crispy and golden brown and the chicken is cooked through at 165F. Using tongs, remove the chicken cutlet from the oil and transfer to a paper towel-lined plate to drain off the grease.
Using a handheld skimmer, remove any crumbs in the oil and bring the temperature back up to 340F (if it dropped) so it’s still bubbling, before adding the next piece of chicken.
Allow the chicken to rest for 2 minutes before slicing. Cut the chicken into 1-inch wide strips.
Serve with some of the katsu sauce, and a side of shredded cabbage, sticky white rice, macaroni salad, and sliced tomato.