Flatten the pork or chicken cutlets to a uniform ½-inch thickness using a meat mallet or rolling pin. Season with salt and pepper, then set aside.

Set up three bowls in a row for breading: one with flour, one with beaten eggs, and the last with panko breadcrumbs. Dredge each cutlet in flour, then dip in egg, and coat with panko.

In a frying pan, heat oil to 350°F (175°C).

Carefully add the breaded cutlets to the hot oil and fry for 3-4 minutes on each side until golden brown. Ensure they reach an internal temperature of 165°F for chicken or 145°F for pork.

Drain the cutlets on paper towels to absorb excess oil and let them rest.

In a bowl, mix together ketchup, Worcestershire sauce, soy sauce, and sugar until well combined.

Spoon white rice into bowls, slice cooked cutlets, and arrange on the rice. Drizzle with tonkatsu sauce and garnish with parsley or green onions.

Serve immediately while hot.