Lay a kitchen towel on the counter. Use the jar lifter to remove a jar from the canner, drain it, and place it on the towel. Keep the remaining jars in the canner, so they stay warm.
Place the canning funnel on the jar. Use a slotted spoon to remove the peppers from the brine and fill the jar. Leave 1/2-inch headspace at the top of the jar.
Ladle the hot brine over the jalapeños and fill the jar while maintaining a 1/2-inch headspace.
Run the bubble popper through the jar to release any trapped air bubbles. Make sure all the peppers are submerged in the liquid. Remove any that stick out, and adjust the headspace again if needed.
Wipe the rim with a clean towel soaked in straight vinegar to remove any sticky residue.
Center a lid on the jar, apply the band over it, and screw it on until fingertip tight. Place the jar back into your canner, and repeat with the rest of the jars.
Once the filled jars are in the canner, adjust the water level to be 2-inches above the tops of the jars.
Place the cover on the canner, and bring it to a boil over high heat. Once the water boils vigorously, set a timer, and continue boiling for 15 minutes for half-pints and pints at altitudes of less than 6,000 feet. Adjust processing time for your altitude if necessary (See Notes).
When the processing time is complete, turn off the heat, remove the cover, and let the canner cool down and settle for about 5 minutes.
Spread a dry kitchen towel on the counter, and use the jar lifter to remove the jars from the canner and place them on the towel. Keep the jars upright, and don't tighten bands or check the seals yet. Let the jars sit undisturbed for 12 to 24 hours to cool.
After 12 to 24 hours, check that the lids have sealed by pushing on the center. The cover should not pop up. If the top flexes up and down, the lid failed to seal. Refrigerate and use up within 3 months.
Remove the screw-on bands and wash the jars. Label, date, and store your jars in a cool, dark place for 12 to 18 months. Allow 4 weeks for the candied jalapeños to develop flavor. Once the jar is open, store it in the refrigerator for up to 3 months. The recipe makes about 8 half-pints or 4 pint jars.