Cut the chicken carcasses into small pieces (I use a pair of kitchen shears).
Place the chicken carcass pieces and chicken feet into a large stock pot.
Fill the pot with water to cover the chicken carcass and chicken feet. Place the pot on high heat.
You will see foams gradually released to the top of the water, as the pot comes to a boil. Remove the pot from the heat.
Discard the blanching water. Rinse the chicken carcass pieces and chicken feet to remove stuck on impurities. Place the clean chicken carcass and chicken feet into the inner pot of an 8-qt Instant Pot.
Roughly chop up onion, carrot, celery stalks; cut the whole head of garlic cross-wise. Add all of them into the inner pot, along with bay leaves, black peppercorns, dried thyme, apple cider vinegar. Add 12 cups of water into the inner pot. Less if it reaches the maximum line.
Place the lid on the Instant Pot and close the pressure valve. Use the "soup/broth" program, and set to "high pressure" for 4 hours.
When cooking is finished, naturally release pressure completely. Remove the Instant Pot lid.
Filter the broth through a fine mesh strainer.
Pour the broth into mason jars and store in the fridge for up to a week.
