Prepare the Beef: Cut the beef chuck roast into large chunks and pat dry with a paper towel.
Sear the Beef: Heat vegetable oil in a large skillet over medium-high heat. Sear the beef chunks on all sides until browned (about 3-4 minutes per side). Transfer to the slow cooker.
Prepare the Sauce: In a small bowl, mix together apple cider vinegar, lime juice, chopped chipotle peppers, adobo sauce, garlic, cumin, oregano, smoked paprika, cloves, salt, and black pepper.
Assemble the Slow Cooker: Pour the spice mixture over the beef in the slow cooker. Add the beef broth, bay leaves, and diced onion.
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 easily shredded.
Shred the Beef: Remove the beef from the slow cooker and shred using two forks. Discard bay leaves.
Mix and Serve: Return the shredded beef to the slow cooker and mix it with the sauce. Let it sit for 15 minutes to absorb the flavors.
Serve: Serve the barbacoa in tacos, burritos, bowls, or over rice with your favorite toppings.