Begin by preparing the chicken breasts. Place each chicken breast between two pieces of plastic wrap and pound them to an even thickness of about 1/2 inch using a meat mallet or rolling pin.

Set up a breading station: In one shallow dish, combine the flour, salt, black pepper, garlic powder, onion powder, and cayenne pepper. In a second dish, beat the eggs. In a third dish, add the panko breadcrumbs.

Dredge each chicken breast in the flour mixture, shaking off any excess. Dip it into the beaten eggs, allowing any excess to drip off, then coat it thoroughly with the panko breadcrumbs.

In a large skillet, heat about 1/4 inch of vegetable oil over medium heat. Once the oil is hot (around 350°F), carefully add the breaded chicken breasts. Fry for about 4-5 minutes on each side, or until golden brown and cooked through.

Once cooked, transfer the chicken to a paper towel-lined plate to drain excess oil. Let it rest for a few minutes before slicing it into strips.

To assemble the bowls, divide the cooked rice among four bowls. Top each bowl with sliced chicken katsu, shredded cabbage, and a drizzle of tonkatsu sauce. Garnish with sliced green onions.