1 cup jalapeño peppers – seeded and finely chopped
1 cup apple cider vinegar (5% acidity)
1.75 ounces powdered fruit pectin
5 cups granulated sugar
Instructions
Prepare a boiling-water canner with a rack; wash 6 half-pint jars, lids, and bands. Heat jars in the canner to keep hot while you cook the jelly; keep lids at room temperature.
Prep the peppers: Remove stems and membranes from the red bell peppers and jalapeños; seed the jalapeños (leave some seeds for more heat if desired). Finely chop to measure 2 cups bell pepper and 1 cup jalapeño.
In a large wide nonreactive pot, combine the chopped peppers and apple cider vinegar. Sprinkle in the powdered fruit pectin and stir until dissolved.
Bring the mixture to a full rolling boil over high heat, stirring frequently to prevent sticking.
Add the sugar all at once, stirring to dissolve. Return to a hard rolling boil that cannot be stirred down and boil for 1 minute, stirring constantly (the boil should be vigorous; the jelly will thicken as it cools).
Remove from the heat. Skim and discard any foam. Working quickly, ladle hot jelly into hot jars, leaving 1/4 inch headspace. Remove air bubbles with a clean utensil, adjust headspace if needed, wipe rims, and apply lids and bands until fingertip-tight.
Place jars on the rack in the canner, ensuring water covers them by 1–2 inches. Bring to a steady boil; process for 10 minutes (start timing when the water returns to a boil).
Turn off heat, let jars rest in the water for 5 minutes, then transfer to a towel-lined surface. Cool undisturbed 12–24 hours until set. Check seals; lids should not flex when pressed. Label and store in a cool, dark place for up to 1 year; refrigerate after opening.