Gather beef chuck roast and short ribs. Cut the beef chuck roast into large chunks. Place the meat in a large pot. Add quartered onion and minced garlic. Combine well.

In a blender, combine dried guajillo and ancho peppers, ground cumin, dried oregano, smoked paprika, salt, and black pepper. Add a little beef broth and blend until you have a thick paste.

Pour the marinade over the meat in the pot. Add remaining beef broth and apple cider vinegar. Stir to coat the meat. Bring to a boil over medium-high heat, then reduce heat to low and simmer for 150 to 180 minutes.

Remove the meat from the pot and shred it using two forks. Heat a skillet over medium heat and lightly toast each corn tortilla for about 30 seconds on each side.

Assemble the tacos by placing shredded meat in the center of a warm tortilla. Top with chopped cilantro and diced onion. Serve with lime wedges and a small bowl of reserved broth for dipping.