Start with toasting the panko bread crumbs. In a nonstick pan, add panko and cooking oil and heat the pan over medium heat. Occasionally stir the panko until it becomes golden brown, about 5 minutes. Turn off heat, transfer panko to a shallow bowl, and set aside while you prepare the chicken.
Next, pound the chicken to get it an even thickness. Take out one chicken breast, place on a cutting board, and lay down a piece of plastic wrap over top. Using a meat pounder or rolling pin, pound the chicken so it is an even thickness, about 1/2 inch. Once flattened, cut the chicken breast in half. Repeat with the second chicken filet. You should have four pieces of chicken.
Season the chicken pieces with salt and pepper. This is the only seasoning for the chicken, so be generous.
Time to set up the dredging station. In a shallow dish, add flour. In a second shallow dish, combine eggs, water, and whisk. The third dish will have the reserved toasted panko bread crumbs. Take a chicken piece and coat it in flour, shaking off the excess. Next, dip the chicken into the egg mixture. Lastly, dip the chicken into the toasted panko, coating evenly. Set the chicken aside, and repeat with the other chicken pieces until all are coated. Preheat the Air Fryer to 375°F. Place the chicken pieces on the Air Fryer basket. Bake the chicken for 10 minutes, flip the chicken and bake an additional 5 minutes.
When the chicken is done, transfer to a cutting board and chop the chicken into bite-sized pieces. Serve with rice, katsu sauce, and shredded cabbage. Enjoy!