Blood pudding, also known as black pudding or blood sausage was pudding made of curdled and boiled pig or cattle blood, mixed with chunks of pork fat, cereal or other vegetables - for texture and juiciness - and spices and other seasoning (depending on regional tastes) then stuffed into a sausage casing. It was called pudding in the old sense of something enclosed in a sausage skin. Blood pudding was extremely popular on Earth in England and Ireland and was usually part of a traditional breakfast.
In 2376 Neelix, in honor of Tom Paris' Fair Haven holoprogram, wanted to prepare a traditional Irish meal. However, he could not decide on a main course. Tom Paris suggested blood pudding, but Neelix said that replicating the lamb's intestines could be tricky. He went on to explain that every time he heated the blood, it coagulated in the milk. Tuvok who could overhear their conversation became increasingly queasy as Neelix talked about the ingredients for the dish and finally left to go see The Doctor. (VOY: "Fair Haven")