In medium saucepan on medium heat, add apple cider, cinnamon, gingerroot, black peppercorns, apple slices, apple cider vinegar, and crushed cardamom pods, cloves, and fennel seeds. Bring to a boil and reduce to a low simmer for 10 minutes. Remove from heat, discard apple slices, and pour apple cider through nut bag or cheesecloth to remove spice remnants. Divide and enjoy!