In a large Dutch oven, heat a bit of oil over medium-high heat. Add the beef and lamb chunks, browning them on all sides.

Remove the meat and set aside. In the same pot, add the chopped onion and garlic, saut?ing until softened.

In a blender, combine the guajillo and ancho chiles, cumin, oregano, black pepper, cinnamon, and 1 cup of beef broth. Blend until smooth.

Pour the sauce into the pot with the onions and garlic, stirring to combine.

Return the meat to the pot, add the remaining beef broth and water. Bring to a boil, then reduce heat to low and cover. Simmer for about 3-4 hours until the meat is tender.

Once cooked, shred the meat and return it to the pot, mixing it with the broth.

Heat a skillet over medium heat. Lightly toast the corn tortillas on both sides.

Fill each tortilla with the shredded meat, and top with chopped onions and cilantro. Serve with lime wedges and the broth for dipping.