If using fresh corn, cut kernels off corn ears. If using canned corn, be sure to drain kernels well several times with fresh water.
Dissolve salt into water in a pint or quart sized mason jar.
Add kernels to jar.
Cover container with a tea towel or clean dishcloth to keep dust and flies out, and secure with twist ties or a rubber band. OR if using small batch fermentation kit, apply the fermentation lid per the instructions.
Ferment 3 to 6 days (until you see it bubbling and has a sour aroma and taste).
If there is any surface yeast or mold, skim it with a spoon or a paper towel. Stir the contents of the jar.
Remove airlock lid and replace with a regular (airtight) lid.
Store in refrigerator. Keeps in brine for up to 2 months.