1. Season beef with salt and pepper. In a small bowl combine cumin, oregano, smoked paprika, minced chipotles + adobo, garlic, onion, broth, lime juice, and vinegar.
2. Add beef to the slow cooker, pour the sauce over top, and tuck in bay leaves.
3. Cook on LOW 8–9 hours (or HIGH 5–6) until the beef shreds easily.
4. Discard bay leaves. Shred the beef in the cooker, then toss in the juices to soak up flavor. Skim excess fat if desired. Taste and adjust lime/salt.
5. Serve barbacoa over rice with black beans and cilantro—or tuck into tacos or burrito bowls.