Prepare your jars and lids for canning by simmering them in a large pot of water until ready to use.

Remove the seeds from half of the jalapenos. Add the jalapenos and 1 cup of vinegar to a food processor or blender; puree until smooth. Add the puree, along with the sugar and remaining vinegar, to a large pot. Bring to a boil; boil for 10 minutes. Add the liquid pectin and return to a boil. Boil 1 minute. Remove from heat.

Use canning tongs (like these) to remove the jars from the hot water. Fill the jars with jelly, leaving 1/4" of space in the top of each jar. Wipe the rims of the jar clean and top with a lid. Screw the rings onto the jar to fingertip tightness. Repeat with remaining jars.

Return the jars to the pot of water. Bring to a rolling boil; boil for 10 minutes.

Carefully remove the jars from the boiling water and let cool. Check the lids for tightness after 24 hours – they should not flex up or down when pressed.

Refrigerate any unsealed jars. Store sealed jars in a cool, dry place.