Optional: 1 tablespoon peppercorns, 2-4 cloves garlic, other herbs like bay leaf, etc.
Instructions
Add all the bones, vegetable scraps and apple cider vinegar to a large stockpot with any other ingredients you'l like to add.
Cover with cold water, add the lid and bring to a roiling boil.
Reduce heat and simmer on low (with lid on) as long as you can - at least 3-4 hours (morning to evening is the best).
Set a container in the sink, put a colander over the top and pour the contents of the pot through, straining out the solids and liquid. (Discard the solids or pull off meat if there is any.)
Transfer the stock to freezer containers, let cool a bit and then seal, label and freeze. Use within a year.
Alternately, you can pour it all into a large stock pot and store it in the refrigerator for a day to be able to skim the fat and then transfer into containers - or make a soup with the stock right in the pot.
Notes
*Or use 3-4 pounds bones from any animal: beef, turkey, or pork to make the corresponding broth.**Technically this is optional, too, but it's important to help draw out the gelatin and other nutrients from the bones, so I'm encouraging you to always use it.