Rinse and drain the jalapeno peppers. Then don a pair of disposable foodsafe gloves, if you have them.
Cut off the stem ends of the peppers, then slice the peppers into rings.
Add the vinegar, sugar, and salt (if using) to a large saucepan (large enough to hold all the peppers later, too). Bring to a boil.
Add the sliced peppers into the boiling brine, and bring it back to a boil. Boil the peppers for 4 minutes (only 2 minutes if you plan to process them in a water bath), stirring occasionally to make sure all the peppers change colour from bright green to a dull green.
Ladle the hot peppers and brine into clean jars. Seal with a lid and let cool. Store the jars in the refrigerator for up to 3 months.
If you choose to process the jars in a water bath, so they can be stored longer (2 to 3 years) unrefrigerated, use sterilized jars and hot lids and process pint jars for 10 minutes using proper canning procedures.
