In a dry skillet over medium heat, toast the guajillo and ancho chiles for about 2 minutes, flipping them occasionally.

Add the toasted chiles, onion, garlic, cumin, oregano, and cinnamon to a blender. Blend until smooth, adding a bit of beef broth if necessary.

In a large bowl, combine the beef chunks with the chile marinade. Cover and refrigerate for at least 1 hour, or overnight for deeper flavor.

In a large pot or Dutch oven, heat a bit of oil over medium-high heat. Brown the marinated beef in batches for about 3-4 minutes per side.

Add the remaining beef broth to the pot. Bring to a boil, reduce heat to low, cover, and simmer for about 1.5 hours until the meat is tender.

Remove the beef from the pot and shred it using two forks.

Strain the broth through a strainer to remove solids.

Return the shredded meat to the strained broth, and season with salt and pepper to taste.

Serve hot, optionally garnished with lime and fresh cilantro.