Season the beef all over with salt and pepper.
For maximum flavor, sear the beef in a hot skillet with oil for 2 to 3 minutes per side, until deeply browned. Alternatively, if you have a sear-and-stew slow cooker, sear the beef directly in the slow cooker insert. This step is optional, but it adds a lot. For true minimum effort, skip it and go straight to the slow cooker.
Blend together the chipotle peppers, adobo sauce, onion, garlic, lime juice, apple cider vinegar, beef broth, cumin, oregano, smoked paprika, chili powder, cloves, and brown sugar until mostly smooth.
Place the beef in the slow cooker, and pour the sauce over the beef. Then add the bay leaves.
Cook on low for 8 to 10 hours or high for 4 to 6 hours, until the beef is fall-apart tender and can easily be shredded with a fork.
Remove the bay leaves. Shred the beef directly in the slow cooker using two forks. Toss the shredded beef in the juices.
For the best texture, leave the lid off and cook on high for another 15 to 30 minutes to let the sauce reduce slightly into the meat. This step is optional but recommended, especially if your barbacoa is super-saucy! Taste and add more salt or lime juice as needed.