Morcilla, also known as blood sausage, is a traditional Spanish delicacy made from pig's blood, rice, and spices. It has a dark color and a rich, earthy flavor. Morcilla is often served grilled or fried and can be enjoyed as a tapa or as an ingredient in various dishes. In Madrid, you can find morcilla served with roasted peppers, in stews, or as a filling for empanadas.