Sear the Meat (Optional): Season the beef chuck roast with salt and pepper. In a skillet over medium-high heat, add the vegetable oil and sear the beef chunks on all sides until browned, about 2-3 minutes per side. This step is optional but adds flavor.

Prepare the Sauce: In a saucepan, combine the beef broth, guajillo chiles, ancho chiles, and chipotle pepper. Bring to a simmer and cook for 5-7 minutes, until the chiles have softened.

Blend the Sauce: Remove the softened chiles from the broth and place them in a blender along with about 1 cup of the cooking liquid. Add the apple cider vinegar, oregano, cumin, cinnamon, garlic, and onion. Blend until smooth.

Cook the Birria:

Assemble in Crock Pot: Place the beef chunks in the crock pot. Pour the blended sauce over the beef, then add the remaining cooking liquid and bay leaves.

Cook Low and Slow: Cover and cook on low for 8 hours or on high for 4-5 hours, until the beef is tender and shreds easily with a fork.

Shred the Beef: Once the beef is tender, remove it from the crock pot and shred it with two forks. Return the shredded beef to the sauce in the crock pot and mix well.

Make the Tacos:

Dip and Fill Tortillas: Heat a skillet over medium heat. Dip a corn tortilla into the birria sauce to coat, then place it in the skillet. Sprinkle a layer of shredded cheese on one half of the tortilla, then add a portion of the shredded birria meat on top of the cheese.

Cook the Tacos: Fold the tortilla over and cook until the cheese melts and the tortilla is crispy, about 2-3 minutes per side. Repeat with the remaining tortillas and meat.

Serve: Serve the birria tacos hot, garnished with fresh cilantro, chopped onions, and a squeeze of lime.