Step 1

Gather all the ingredients. Adjust an oven rack to the middle position and preheat the oven to 400ºF (200ºC). For a convection oven, reduce cooking temperature by 25ºF (15ºC). Line a rimmed baking sheet with parchment paper.

Step 2

Combine the panko and oil in a frying pan and toast over medium heat until golden brown. Transfer panko into a shallow dish and allow to cool.

Step 3

Butterfly the chicken breast and cut in half. Using a mallet or rolling pin, pound the chicken to equal thickness if necessary. Season salt and pepper on both sides of the chicken.

Step 4

In a shallow dish, add flour and in another shallow dish, whisk together the egg and water.

Step 5

Coat each chicken piece in the flour and shake off any excess flour. Dip into the egg mixture and then coat with the toasted panko, pressing firmly to adhere to the chicken.

Step 6

Place the chicken pieces on the prepared baking sheet (I recommend putting on a wire rack as I did in this recipe) and bake at 400ºF (200ºC) until the chicken is no longer pink inside (internal temperature should be 165ºF (74ºC)), about 25-30 minutes. Serve immediately or transfer to a wire rack so the bottom of the katsu doesn't get soggy from the moisture.

Step 7

Serve with salad and tonkatsu sauce on the side.

Step 8

You can keep the leftovers in an airtight container and store in the refrigerator for up to 3 days and in the freezer for a month.