In a large skillet, heat the 1 tablespoon oil over medium-high heat. Begin to brown the beef ribs in batches until browned on both sides, about 3 to 4 minutes per side. Place them inside a large 6-quart slow cooker once they've browned.

In a blender, combine the whole can of chipotle peppers with the adobo sauce, 4 cloves garlic, can of tomato paste, 1/4 cup lime juice, 2 tablespoons apple cider vinegar, 1 tablespoon cumin, 1 tablespoon kosher salt, 1/2 cup beef broth, and the 1/2 chopped onion (mince the remaining half for serving). Blend until the sauce is homogenous. Transfer to the slow cooker and pour over the beef. Add the bay leaves.

Cover and cook for 6 hours on high or 10 hours on low, until the meat is falling off the bone. Moving the ribs in the sauce every once in a while so they cook evenly.

Remove the ribs from the sauce. Remove any excess fat from the ribs; discard the bones and shred the meat. Using a large spoon, skim the fat from the surface of the sauce in the slow cooker. Transfer the meat back to the slow cooker and combine with the sauce.

Serve the beef inside warm tortillas and top with the reserved minced onions, avocado, cilantro, and a lime wedge for squeezing.