> for which I don't know the English word - it's a grayish slab, often eaten on rye bread here in North-Western Europe

In British English, that would be "Head Cheese" or "Brawn", or at least head cheese is likely to be a similar product, made from the animal's head, that's the only thing I can think of. I've never eaten it and it's regarded as kinda gross.

Now blood sausage, that can be tasty :)