Either pork fillet or pork loin, is sliced. It is then coated in flour, dipped into beaten eggs, and rolled in breadcrumbs. It is then fried in hot oil. People often use a Japanese Worcester sauce, but some use a vinegar-soy-sauce called ponzu when they eat it. Tonkatsu originated as a cutlet, but it is also used as a sandwich filling or in combination with curry. 