The Preparation
Finely dice or process jalapeños in a food processor (remove seeds for milder jelly, keep for hot).
Combine jalapeños and vinegar in a large pot and bring to a boil.
Add sugar all at once and stir to dissolve. Return to a rolling boil.
Add liquid pectin and butter. Return to a full rolling boil and boil hard for 1 minute, stirring constantly.
Remove from heat and skim any foam.
Ladle hot jelly into sterilized jars, leaving 1/4 inch headspace.
Wipe rims, apply lids, and process in a water bath canner for 10 minutes.
Let cool undisturbed. Jelly will set as it cools.
