2 lb bones
2 tbsp Apple cider vinegar
1 # onion
2 cloves garlic

Recipe source: https://wellnessmama.com/5888/bone-broth/

Next time try it in the Instant Pot.

This takes 24 hours of cooking to make.
Put the bones in a large pot and fill it with cold water.
Add vinegar.  The acid brings out nutrients from the bones.
Let sit 20-30 min without cooking yet.
Chop vegetables except garlic, add to pot.
Optionally, add spices such as parsely, salt and pepper.
Bring to a boil, then simmer.
Simmering lasts about 24 hours.  For the first couple hours, you have to check it every half hour and skim the frothy layer off the top with a big spoon.
During the last 30 min, add the garlic (and if using fresh herbs, add them here too).
Strain it to remove the bones and vegetables.