Place chicken, or turkey carcass in Instant Pot.
Add vegetable scraps, vinegar, peppercorns, salt, garlic and herbs.
Fill with water until the max line.
Cover the Instant Pot, make sure the valve is set to sealing.
Set it to Manual for 2 hours on high pressure. (Cooking the stock for this long ensures nice and thick, flavorful gelatinous stock.)
Then let it release pressure naturally, meaning just leave it alone for a while, usually about an hour or so. (Warning!Because the Instant Pot is full of hot soup, quick release is not safe!! If you absolutely need to, you can do natural release for at least 30 minutes, and then turn the valve to venting to release the remaining pressure.) Be very careful when opening the lid.
Now you can let the stock cool for a little bit so it's easy to handle. Place a colander over a large bowl and carefully pour the stock. (I love these mini mitts to hold the hot pot!) Remove the colander with bones and vegetables. If desired, strain the stock through a fine mesh strainer for clearer stock. Cover and refrigerate overnight.
The next day, scrape off the fat cap. Divide the stock into containers, leaving space for liquid to expand, and freeze. For convenience, freeze in 1-, 2- and/or 4-cup volumes for different recipes.