Morcilla is a traditional blood sausage originating from Spain. It's the first type of sausage that's made during the pig slaughter – the ground pork is mixed with pig's blood, onions, spices and seasonings, and fillers such as rice. The mixture is stuffed into casings, formed into cylindrical shapes, shortly boiled in order for the blood to coagulate, and the morcilla is then hung up to cure.
Nowadays, there are many morcilla varieties throughout the country, but the blood sausage is usually cut into thick slices, fried in olive oil, and eaten as a tapa or a pintxo (pincho), or it's used in stews and bean dishes. Some cooks like to boil it in cider.