Sterilize your jars.
Bring a small pan of water to a boil and place lids in water to soften the rubber seal. Allow them to sit in pan until you are ready to lid the jars.

Wear disposable gloves to protect your hands from the pepper oil.

Wash and dry the peppers and slice into rings 1/4” thickness or dice them. The more seeds you use the hotter this gets. I discard some seeds.

In a medium saucepan, bring the vinegar, water, salt and sugar to a boil. Add the peppers and garlic to the vinegar water, stir then remove from heat. Allow the peppers to set in the brine solution for 15 minutes. The jalapeños will turn from bright green to a darker shade.

Pack your jars with peppers and brine leaving a 1/2" head space at the top. Use a chop stick or dinner knife and go around the inside of the jar to release trapped air pockets. Add more peppers if needed. Wipe the jar rim with a damp paper towel to remove any bits of brine or peppers. Apply a jar lid and twist a lid ring fingertight on the jars.

Bring a large canner or stock pot of water to a boil. Gently lower jars into boiling water. The boiling water should be 1" above jars. Water bath for 10 minutes, remove jars and allow to cool. Listen for your lids to pop Indicating your jars are sealed and ready for storage. If a lid doesn't seal refrigerate for use.

Sealed canned jalapeños will last up to a year. Refrigerated open jar will last several months.