Add vegetables to a slow-cooker and top with bones.

Drizzle with vinegar and fish sauce. If fish sauce is unavailable, use 1 tablespoon of sea salt. 

Cover with water, about 12 cups, until all ingredients are submerged.

Turn slow-cooker to high. Once boiling, turn heat down to low and let the broth cook for at least 24 hours. 

If there is a gritty film, scrape with a spoon and discard before straining.

Strain the broth and discard the bones and vegetables.  Taste to adjust salt, if preferred.

Store broth in jarring cans in the refrigerator for a couple of days or freeze for a few months.