Cut 450 g chicken breast into slices about 2cm thick.
Stab the surface of the chicken slices with a fork and sprinkle with a few pinches of salt and pepper.
Transfer to a bowl and add 1 tbsp all-purpose flour. Mix until all the slices are evenly coated.
Add 2 tbsp Japanese mayonnaise to the bowl and mix until fully covered. Set aside for later.
Pour 50 g panko breadcrumbs into a dry pan and heat on medium. Stir frequently and heat until nicely browned, then remove from the stove and transfer to a plate or container.
Preheat your oven to 220 °C (428 °F). Once the breadcrumbs are cool enough to touch, coat the chicken generously. Lightly grease a wire rack and place it over a baking tray.
Arrange the chicken pieces on the rack and once the oven is hot, place the tray on the bottom shelf and bake for 10 minutes. After 10 minutes, flip and bake for a further 15 minutes.
While the chicken katsu is baking, mix the sauce ingredients together in a small bowl.
Remove the chicken from the oven and serve immediately. Drizzle with the sauce or serve on the side for dipping. Enjoy!