How to Make It
Stir broth, onion, garlic, chipotles, adobo sauce, cumin, oregano, and 1¼ teaspoons salt in a 6- quart slow cooker. Add beef and turn to coat. Cover and cook on low until beef is very tender and pulls apart easily, 7 to 8 hours.
Transfer beef to a large bowl; coarsely shred with 2 forks. Toss beef with 1½ cups cooking liquid and ¾ teaspoon salt.
Toss coleslaw mix with cilantro, oil, lime juice, and remaining ¼ teaspoon salt in a medium bowl. Divide beef among buns; top with slaw and pickled jalapeño slices, if using.