If chicken feet still have yellow membranes on the outside, prepare a blanching station. Set an ice-bath next to a pot of boiling water. While the water heats, rub the chicken feet with salt.

Once boiling, use a slotted spoon to add the feet and submerge. Quickly remove and place in the ice-bath to prevent cooking.

Peel the yellow membrane from the outside and discard.

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

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

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

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.