1. In a large pot, add the beef, beef broth, guajillo chiles, ancho chiles, onion, garlic, oregano, cumin, bay leaves, salt, and pepper. Bring to a boil.
2. Reduce heat to low and simmer for about 4 hours, until the meat is tender and shreds easily.
3. Remove the meat from the pot and shred it using two forks. Set aside.
4. Blend the remaining liquid and solids from the pot until smooth. Return the sauce to the pot.
5. Dip the tortillas in the sauce, then cook them on a hot skillet until slightly crispy.
6. Fill the tortillas with the shredded beef, cilantro, onions, and a squeeze of lime. Serve with extra sauce for dipping.