1. Add the apple cider, apple cider vinegar, kosher salt, shallot, garlic, bay leaves, and rosemary sprigs to a medium pot and bring to a boil. Continue boiling for two minutes then transfer the contents to a large bowl.
2. Add the ice cubes and once they have melted, add the pork loin making sure it is submerged. Cover and refrigerate for 8-24 hours.