There is no clear definition of butcher's dish. To put it simply, butcher's dish is not a specific dish. The name of butcher's dish means what we call the Pork Encyclopedia. You must have heard of this. Well, there are many restaurants like this in the Northeast, and pork blood sausage and sauerkraut are just one of the distinctive dishes. There are many more, such as buckwheat sausage, deboned meat, big bones, skin jelly, and many more. You can eat anything from pigs.
Maybe in the past, people were not very wealthy and could only eat so much during the New Year when pigs were killed, so they were named pig-killing vegetables.