Preheat oven to 450ºF.

Place bones and onion in a roasting pan.

Bake for 30 minutes or until bones are browned.

Remove from oven.

Place bones and onion in a large stockpot.

Add water, vinegar, celery, carrot, parsley, garlic, and bay leaves to the stockpot and bring to a boil.

Reduce heat, cover and simmer for 3 hours.

Strain and discard vegetables and bones— save the meat for later use or another recipe.

Refrigerate and use within 3 days, or freeze.