For good flavour and nutrition, a beef marrow bone is a great addition to this bone broth. Make up the rest with chicken carcasses from roasts or lamb bones, which are also good for a rich flavour.
The birria can be eaten in a bowl like a soup, or in tacos or ... Once all the beef is browned, return it to the casserole, add the marrow bone, the adobo and 2 litres/3½ pints water.