Prepare the Chiles: In a dry skillet over medium heat, toast the guajillo and ancho chiles for about 1-2 minutes until fragrant, ensuring not to burn them. Remove from heat and let them cool slightly, then transfer to a blender.
Make the Sauce: Add to the blender the quartered onion, minced garlic, ground cumin, oregano, smoked paprika, cinnamon, apple cider vinegar, and 1 cup of beef broth. Blend until smooth.
Season the Meat: In a large bowl, season the beef chunks with salt and pepper.
Combine in the Crockpot: Place the beef chunks in the crockpot and pour the blended sauce over the meat. Add the remaining beef broth to cover the meat.
Cook: Cover and cook on low for 8 hours or on high for 4-5 hours until the beef is tender and easily shredded.
Shred the Meat: Once cooked, remove the beef from the crockpot and shred it with two forks.
Warm the Tortillas: In a skillet over medium heat, warm the corn tortillas for about 30 seconds on each side until they are pliable.
Assemble the Tacos: Place a generous amount of shredded beef in the center of each tortilla.
Garnish and Serve: Top with fresh chopped cilantro, serve with lime wedges, and drizzle some of the broth from the crockpot over the tacos for extra flavor.