Add 2 lb more or less of un-roasted peanuts in shell to crockpot or pot
Add 1/2 cup apple cider vinegar
Add 1/2 cup kosher salt
Add 1 Tbs. red pepper flakes
Fill crockpot with water, or several inches over height of dry peanuts in pot
Crockpot on "high" or "low" if using stove, for 8 hours at least
Peanuts should open easily, and nuts should be very soft without any crunch.
This is a very simple and plain recipe without much spice, there are many variations out there. This one has a delightfully mild sourness from the vinegar. Keeps in the fridge for a week.