In a very large pot, bring water to a boil. Submerge glass mason jar and lid, and continue boiling for at least 12 minutes to sterilize. Use tongs to remove jar and lid, and place on a clean kitchen towel to dry. Keep large pot on the stove to process jar later.

If using a juicer, juice bell peppers; reserve juice and bell pepper pulp and set aside. Otherwise, use a food processor to finely mince bell peppers.

Place a small plate in the freezer. In a large, heavy-bottomed saucepan, combine bell pepper juice and pulp (or minced peppers), chopped jalapeños, apple cider vinegar, and sugar. Bring to a rolling boil over high heat and boil for 10 minutes, stirring often. Add fruit pectin, stirring constantly for 1 minute. Take chilled plate out of freezer and dab a small amount of jelly on plate. Return plate to freezer for 1 minute. If jelly has jelled and does not slide down when the plate is tilted, then it is done. However, if the jelly slides down, continue to cook for another minute, and try the freezer test again. Continue cooking until jelly reaches the desired consistency.

Ladle hot jelly into hot jars using a funnel, leaving at least 1/4 inch of headspace. Wipe rims clean, apply lids, and screw metal bands on firmly.

In the large pot of boiling water, lower jarred jelly, submerging jar in at least 2 inches of water. Process for 10 minutes. Use canning tongs to carefully remove hot jar, and then set it in a cool, dark place. As the jar cools, listen for the lid to snap, signaling a proper seal. If jar does not seal correctly, then refrigerate once it cools to room temperature and use within two weeks. Refrigerate upon opening. Discard opened jar after two weeks.