Add the Katsu sauce ingredients to a small bowl. Mix together until combined. Set aside.
Remove the chicken tender from each breast and save them for another recipe. (This makes the chicken easier to work with.) Season the chicken generously on both sides with salt and pepper.
Use shallow bowls to set up a dredge station with flour in the first bowl, beaten eggs in the second bowl, and panko in the third bowl. Dip the chicken into the flour, then the eggs, and finally the panko, coating each breast completely.
Place a large skillet over medium heat and add the oil. Once hot (300F, but not over 325F), fry each chicken breast for 3-4 minutes per side until golden brown and cooked through. Transfer to a paper towel-lined platter to drain. (I cooked the chicken in two batches.)
Drizzle with Katsu sauce and serve warm over shredded green cabbage alongside cooked white rice. Garnish with sliced green onions if desired.
Notes
Nutritional information includes one chicken breast and 2 tablespoons of sauce.