Place the apples, fennel, onion, and garlic in the bottom of a slow cooker. In a small mixing bowl, mix together the ground cinnamon, salt, pepper, cumin, mustard, and 1 tablespoon of apple cider vinegar to form a paste. Spread the bacon fat over the top of the pork, then spread the spice paste over the top and sides of the meat. Carefully place the pork on top of the vegetables in the slow cooker. Add the remaining 3 tablespoons of apple cider vinegar, water, and cinnamon sticks to the bottom of the slow cooker.