Tonkatsu, invented in the 1930s, is one of the most popular dishes in Japan. It consists of a breaded deep-fried pork cutlet, and is generally served with shredded cabbage, white rice, and miso soup. It is eaten with a brown sauce, the ingredients of which vary from place to place but which has a taste close to Worcestershire sauce. Some people also like to eat their tonkatsu with a spicy yellow mustard.
When ordering tonkatsu, diners generally specify either a hire (lean) or rosu (fatty) cut. The very finest tonkatsu is made from kuro buta (black pig) from Kagoshima prefecture, in southern Japan.