Begin by preparing the dried peppers. Place the guajillo and ancho peppers in a dry skillet over medium heat for about 2 minutes until fragrant. Be careful not to burn them.
After toasting, transfer the peppers to a blender along with the chopped onion, garlic, oregano, cumin, chili powder, smoked paprika, salt, black pepper, and one cup of beef broth. Blend until smooth, adding more broth if necessary to assist with blending.
In the Crock Pot, add the beef chunks and pour the blended sauce on top. Add the remaining beef broth and bay leaves, stirring everything to combine.
Cover the Crock Pot and set it on low heat for 8 hours or high heat for 4 hours, until the beef is fork-tender.
Once cooked, remove the beef from the sauce and shred it using two forks. Strain the cooking liquid through a fine mesh sieve to remove any solids.
Heat a skillet over medium-high heat and lightly toast corn tortillas on both sides, about 30 seconds to 1 minute per side until they're pliable.
Dip each tortilla into the strained broth briefly, then layer it with shredded beef. Top with fresh cilantro and diced onions. Optionally, add a drizzle of broth over the filling for more flavor.
Serve hot with lime wedges on the side for an extra zing!