Wash and select fully mature, but still green peanuts. They must not be roasted or already cooked or dried. Fully mature peanuts do not make good quality boiled peanuts; rather raw or "green" ones are used.
Soak the peanuts in the shell in fresh water for one hour.
Discard the water, cover again with fresh water and soak for another hour.
Repeat this soaking process one more time for another hour. This makes a total soaking time of three hours, using fresh water each time.
Put the canning jars in boiling water for 10 minutes to sterilize. Remove and drain.
Put lids in a small pot of almost boiling water for 5 minutes, then use the magnetic lid lifter wand to pull them out.
Combine 1 cup of pickling salt or kosher salt with 1 gallon of water. Set this on a burner on low heat (so it does not boil away) until you are ready to fill the jars
Get a very large pot of boiling water going, enough to hold all the peanuts you plan on canning and room for extra water. Then parboil (simmer just below the boiling point) the peanuts for 10 minutes in fresh water and drain.
Pack the hot peanuts into hot jars, leaving ½ inch head space
Fill each jar to ½ inch from the top with boiling brine (1 cup salt per gallon of water). Remove any air bubbles.
Add 1/2 to 1 teaspoon of cajun seasoning, depending on how spicy you like it. (optional)
Wipe the jar's rims, put the lids on then the rings and tighten them snugly. Place the jars into the weighted gauge pressure canner with 4 inches of water in the bottom. Please follow your own canner's instruction book on how to use a canner.
Lock lid on pressure canner, put the heat on high and let the steam escape through the vent for 10 minutes to purge the airspace inside the canner
After 10 minutes of venting, put the weight on and close any openings to allow the pressure to build to 11 pounds
Once the gauge hits 10 pounds, set your timer for 90 minutes, controlling heat to keep at 10 pounds pressure.
When processing time is over, turn off the heat, and allow the pressure canner to cool and the pressure to drop to zero before opening the canner lid
Lift the jars out of the water and let them cool on a towel, without touching or bumping them.