01 - In a small bowl, combine ground cumin, dried oregano, smoked paprika, sea salt, black pepper, and cinnamon. Mix thoroughly until evenly incorporated.
02 - Place the chuck roast chunks into the slow cooker. Sprinkle the spice blend over the beef and toss well to ensure each piece is evenly coated on all sides.
03 - Scatter the chopped onion, minced garlic, chopped chipotle peppers, and jalapeño over and around the seasoned beef in the slow cooker.
04 - In a separate bowl, whisk together the fresh lime juice, apple cider vinegar, beef broth, and tomato paste until smooth. Pour the mixture evenly over the beef and vegetables in the slow cooker.
05 - Tuck the bay leaves into the liquid. Cover the slow cooker and cook on LOW for 8 hours, or until the beef is fork-tender and pulls apart effortlessly.
06 - Remove and discard the bay leaves. Using two forks, shred the beef directly in the slow cooker, mixing it thoroughly with the accumulated cooking juices.
07 - Serve the barbacoa hot in warm corn tortillas, burritos, or over rice. Garnish with fresh cilantro, diced onion, and lime wedges as desired.