Begin by preparing the chicken. Place each chicken breast between two sheets of plastic wrap and pound them to an even thickness of about 1/2 inch.

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

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

Heat the vegetable oil in a large skillet over medium heat. Once hot, carefully add the breaded chicken breasts. Fry for about 4-5 minutes on each side, or until golden brown and cooked through (internal temperature should reach 165°F). Remove from the skillet and let drain on paper towels.

While the chicken is resting, prepare the bowls. Divide the cooked rice among four bowls. Top each bowl with shredded cabbage, sliced cucumbers, and chopped green onions.

Slice the crispy chicken katsu into strips and place on top of the rice and vegetables. Drizzle with tonkatsu sauce before serving.