Place the sliced onion and minced garlic in the bottom of the slow cooker. Set the pork shoulder on top.
In a small bowl, stir together the chicken broth, chili powder, cumin, salt, and black pepper. Pour the mixture over the pork.
Cover and cook on low for 8 hours or until the pork shreds easily with two forks.
While the pork cooks, make the slaw. In a medium bowl, whisk together the mayonnaise, apple cider vinegar, and honey. Add the shredded cabbage and carrot, then toss until everything is coated. Cover and refrigerate until serving.
When the pork is done, remove it from the slow cooker and shred it on a cutting board. Return the shredded meat to the slow cooker and stir it into the juices.
Warm the corn tortillas. Fill each tortilla with pulled pork and top with a spoonful of slaw.