Place bones and apple cider vinegar into a large crockpot or slow cooker, then cover with cold, filtered water.  Place on lid and allow bones, vinegar and water to rest at room temperature for about one hour.

Add vegetables and bring to a high simmer.  Once you have a high simmer, reduce the heat to low and let the broth simmer for 12 hours. If using a slow cooker, set it to low after you’ve brought the broth to high simmer first, and cook for the same time.  You can keep topping up with filtered water if needed.

Once it has finished cooking you want to cool it as quickly as possible to avoid any bacteria risks.  Skim off any impurities from the top, strain out the bones and veggies and add some ice to the broth.  Portion into smaller serves, place one in the fridge to be used in a few days and the rest in the freezer for 3 months.