To a crockpot, add chicken carcasses and top with frozen vegetables.
Cover chicken and vegetables with seasonings and apple cider vinegar.
Fill crockpot to top with water and cook on high for 6 hours.
In a large casserole dish, add a strainer and strain contents of crockpot into casserole dish. You may need a second casserole dish.
Pour contents that remain in strainer into a Ziplock bag, close and discard.
Cover the casserole dishes with plastic wrap and very carefully move the casserole dishes once they have cooled some to the refrigerator and let cool overnight.
The next day, remove the casserole dish. If you wish to remove the layer of fat from the top, you can skim the fat off the top. I keep the fat on mine when I'm using my stock for a casserole with rice. If you're using this recipe for a soup or stew, I recommend skimming the fat off.
Spoon out 4-6 cups of stock into freezer size gallon bags. It will be very gelatinous which is good for you! Don't worry, it reduces back to a liquid state when warmed.
Lay freezer bags flat in freezer.
To thaw, you can either move the bag to your refrigerator one day prior to use, run the bag under room temperature water or add the contents straight to a stock pot to heat up. Use it just as you would a regular stock or broth.