• Season the beef chunks with salt and pepper. In a large skillet, heat olive oil over medium-high heat. Sear the beef chunks (in batches) on all sides until browned. Remove and set aside.
• Gently wash the dried chilies. Cut them open and remove the stems and seeds.
• Place the halved onion and halved garlic head into the crockpot. Add the seared beef with juices, dried chilies (whole and seeds removed), halved serrano peppers, tomatoes, water, ground cumin, dried Mexican oregano, cinnamon stick, cloves (if using), and bay leaves. Stir to combine.
• Cook on low for 8-10 hours or on high for 4-6 hours, until the beef is tender and easily shreds with a fork.
• About halfway through the cooking process, squeeze the garlic out of the clove. Remove the softened chilies, tomatoes, onion, and serrano peppers with tongs. Blend them with some of the cooking liquid until smooth, and return the blended mixture to the crockpot. Stir to combine.
• Remove the cinnamon stick, cloves, and bay leaves. Shred the beef with two forks and mix with the cooking liquid. Stir in the lime juice and add more salt if desired.

Make the Tacos

• Heat corn tortillas on a skillet or griddle until pliable. Coat each tortilla in the rich birria broth.
• Place shredded birria meat and grated Oaxaca cheese or Monterey Jack cheese on each dipped tortilla, fold in half, and fry on the skillet until crispy and slightly browned.
• Add toppings like chopped onion, cilantro, lime juice, and sliced jalapeño. Serve with extra lime wedges and birria broth for dipping.