Prepare the chiles by removing stems and seeds.
Toast the chiles in a dry skillet over medium heat for 1-2 minutes.
Blend toasted chiles with garlic, onion, cumin, oregano, and cinnamon.
Season the beef with salt and pepper, then place it in the Crockpot.
Pour the blended sauce and beef broth over the meat in the Crockpot.
Cook on low for 8 hours or high for 4 hours.
Once cooked, shred the beef with two forks.
Warm corn tortillas in a skillet.
Assemble the tacos with meat, cilantro, and lime.
Serve and enjoy with broth as a dipping sauce.