Pork encyclopedia, you must have heard of this. There are many such restaurants in the northeast, and pork with blood sausage, sauerkraut and pork is just one of the specialties. There are many more, such as buckwheat sausage, torn flesh and blood, big bones, frozen skin, and so on. You can eat anything from pigs.
It may be that people were not very rich before, and they could only eat so much to kill pigs in the New Year, so they named it "killing pigs".