Step 1: Prepare your jalapeños. Wash them thoroughly. If you prefer less heat, carefully remove the seeds and white pith using a small spoon or knife (wear gloves!). Slice the jalapeños into uniform 1/4-inch thick rounds.
Step 2: Prepare your jars. Wash two pint-sized glass jars and their lids with hot, soapy water. For quick pickles, hot clean jars are sufficient. For longer storage, you can sterilize them by boiling in water for 10 minutes or running through a hot dishwasher cycle.
Step 3: Make the pickling brine. In a medium saucepan, combine the water, white vinegar, pickling salt, and granulated sugar. If using, add sliced garlic cloves and black peppercorns to the brine. Bring the mixture to a rolling boil over medium-high heat, stirring occasionally until the salt and sugar are completely dissolved. Let it boil for 2-3 minutes.
Step 4: Pack the jars. Carefully and tightly pack the sliced jalapeños into the prepared jars. You can really press them down to fit as many as possible.
Step 5: Pour the brine. Carefully pour the hot pickling brine over the packed jalapeños in the jars, ensuring they are completely submerged. Leave about 1/2 inch of headspace from the rim of the jar. Tap the jars gently on the counter to release any air bubbles; add more brine if needed to maintain headspace.
Step 6: Seal and cool. Wipe the rims of the jars clean with a damp cloth, then secure the lids tightly. Allow the jars to cool completely at room temperature (this can take several hours). As they cool, a vacuum seal may form.
Step 7: Refrigerate and enjoy. Once cooled, transfer the jars to the refrigerator. While you can taste them after a few hours, the flavors will develop and deepen significantly after at least 24 hours. For best flavor, wait 2-3 days before enjoying. Your homemade quick pickled jalapenos will last several weeks (up to 2-3 months) in the refrigerator.