Wikipedia
Moronga
Moronga, rellena, or morcilla is a sausage made of pig's blood. It is found in Cuba, Puerto Rico, Central America and Mexican cuisine. Spices, herbs (such as ruta, oregano, and mint), onions and chili peppers are added and then boiled in the pig's large intestines for casing for several hours. It is served in a sauce, either "chile rojo" or "chile verde". Considered a delicacy, it is also served in Mexico as a filling in gorditas and tacos after it has been pan-fried with fresh onions and jalapeño peppers.