Tonkatsu is deep-fried breaded pork loin or medallion. It is often served with Worcestershire sauce. Breading thick slices of pork seals juiciness of meat inside while finishing outside crispy. Tonkatsu is one of the popular Japanese food among non Japanese.
It is beleived the origin of the word Tonkatsu comes from cutlet in French. It was introduced to Japan in the late 1800s. People used to shallow-fry pork with less oil in the beginning and started to cook like what we know of today 60 years later, in the begging of 1900s.