Place the dried chiles in a saucepan with 3 cups of water. Bring to a boil, then remove from heat and let them rehydrate while you prepare other ingredients.

Toast the black peppercorns, coriander seed, bay leaves, and cinnamon stick in a dry skillet over medium-high heat for a couple of minutes until fragrant. Transfer to a cheesecloth and tie with kitchen twine to create a spice sachet. (Alternatively, grind the toasted spices).

Cut the beef chuck roast into large chunks and season generously with sea salt. Heat avocado oil in a large cast iron skillet over high heat until very hot. Sear the beef chunks on all sides until deeply browned. Transfer the seared beef to a slow cooker.

In the same skillet, sauté the chopped onion over medium-high heat until softened. Add the minced garlic, tomato paste, ground cumin, and dried oregano, and cook for another 3 minutes until fragrant. Transfer this mixture to the slow cooker with the beef.

Remove stems from the rehydrated chiles. Add the chiles and their soaking water to the slow cooker, along with the beef broth, apple cider vinegar, and the spice sachet. Stir to combine, ensuring the beef is mostly submerged in liquid. Cover and cook on low for 8-10 hours.

Once cooked, remove the meat from the slow cooker and transfer to a cutting board. Shred the meat using two forks to your desired consistency and place in a large bowl.

Transfer the cooked chiles to a blender with about 2 cups of the braising liquid from the slow cooker. Blend until completely smooth. Pour this blended sauce back into the slow cooker with the remaining liquid. This liquid will be used for dipping the tortillas and as a sauce.

Heat a large cast iron skillet with a generous amount of oil over high heat. Dip each corn tortilla in the birria sauce, then place it in the hot skillet. Sprinkle with cheese, then add shredded meat to one half of the tortilla. Fold the tortilla in half to create a taco.

Drizzle more sauce over the taco, then flip and repeat for the other side. Continue cooking and flipping until the taco is golden brown and crispy to your liking.

Serve the birria tacos immediately with pickled red onions, fresh cilantro, and a side of the consommé for dipping.