Wearing gloves, slice the jalapeño peppers into thin slices.
In a medium-sized saucepan, bring the vinegar, water and canning salt to boil.
Carefully pour the prepared brine over the peppers, leaving a 1/2-inch headspace in the jar.
For refrigerator pickles, simply allow the jars to cool and then store in the refrigerator. They should keep for several weeks.
If canning, process the jar in a water bath canner for 10 minutes (adjusting for altitude, see notes). When properly processed, they should maintain peak quality on the pantry shelf for 12-18 months.
Notes
If you're canning at an altitude of 1,000 feet to 6,000 feet, process the jar for 15 minutes. Above 6,000 feet in elevation, process jars for 20 minutes.