Step 1: Lightly toast the dried chilies in a skillet over medium heat for 1-2 minutes until fragrant. Place them in a bowl of hot water to soak for 20 minutes.
Step 2: In a blender, combine the soaked chilies, garlic, vinegar, oregano, cumin, cloves, and 1 cup of the soaking liquid. Blend until a smooth paste forms.
Step 3: Season the beef chunks and shanks generously with salt and pepper. In a large Dutch oven, sear the meat in oil over high heat until browned on all sides. Remove the meat and set aside.
Step 4: In the same pot, sauté the onion halves briefly, then pour in the chili paste and beef broth. Return the meat to the pot along with the cinnamon stick.
Step 5: Bring to a boil, then reduce heat to low, cover, and simmer for 3 to 4 hours, or until the meat is extremely tender and easily shreds with a fork.
Step 6: Remove the meat from the pot and shred it using two forks. Skim the reddish fat from the top of the consommé and reserve it in a small bowl.
Step 7: To assemble the tacos, dip a tortilla into the reserved fat and place it on a medium-hot griddle. Add cheese and shredded beef, fold the tortilla, and cook until crispy on both sides.
Step 8: Serve the tacos hot with a small bowl of the strained consommé on the side, topped with cilantro and onion.