Step 1

Before you begin, prepare calcium water.To do this, combine ½ teaspoon calcium powder (in the small packet in your box of Pomona’s pectin) with ½ cup water in a small, clear jar with a lid. Shake well.Extra calcium water should be stored in the refrigerator for future use.

Step 2

Wash and rinse jars, lids, and screw bands. Set screw bands aside until ready to use. Place jars in boiling water bath canner with a rack, fill at least 2/3 of the way full with water, and bring to a boil. Boil jars for 10 minutes to sterilize (add 1 additional minute of sterilizing time for every 1000 feet above sea level), then turn down heat and let jars stand in hot water until ready to use. Place lids in water in a small pan, bring to a low simmer, and hold there until ready to use.

Step 3

Peel the onions and discard the skins. Slice the onions very thinly, and then cut the thin slices into approximately one-inch lengths. Place sliced onions in a sauce pan – ideally, a heavy-bottomed one that conducts heat evenly. Add the salt, then mix.

Step 4

Put the pan on the stove, cover the pan with a lid, and cook the onions over medium to medium-low heat for about 5 minutes. While the onions are cooking, occasionally lift the lid and give the onions a quick stir to be sure that they are not starting to burn. If they are, reduce the heat slightly, replace the lid as quickly as possible, and keep cooking. If the onions are really sticking, you may add a very tiny bit of the apple cider to ease the sticking, but only do this if it's really necessary.After 5 minutes or so, the onions should have caramelized a good bit, and should begin to have a nice golden-brown color. If not, cook the onions for a little bit longer, with the lid still on, to achieve this. At this point, when the onions have really started to brown, they'll probably want to start sticking. So, remove the lid, reduce the heat if necessary, and stir constantly, scraping off and incorporating the brown bits on the bottom of the pot as necessary for a couple more minutes. This will allow the onions to continue to brown and caramelize while preventing burning.

Step 5

After the onions are caramelized and well-browned, add the apple cider, the vinegar, and the pepper to the onions. Increase the heat and bring the mixture up to a boil. Cook the mixture at a low boil for a couple of minutes, stirring frequently, to allow the liquid to reduce in volume.

Step 6

Remove the pan from the heat, then measure the mixture. (A large-capacity, heat-tolerant measuring container works well for this, as it allows you to transfer the mixture from the pan directly into the measuring container). If the quantity of the mixture is more than 4 cups, place the mixture back in the pan and allow it to continue cooking until you have reduced the quantity to 4 cups, measuring as necessary to confirm quantity. If you find that you have less than 4 cups, add a small, additional amount of apple cider to bring the total quantity of the mixture back up to 4 cups. Transfer the onion mixture back into the sauce pan, add calcium water, and then stir to combine.

Step 7

In a separate bowl, combine the maple syrup and pectin powder. Mix well and set aside.

Step 8

Bring the onion mixture to full boil over high heat. Add the maple syrup-pectin mixture, and then stir vigorously for 1 to 2 minutes, still over the highest heat, to dissolve pectin. Return the jam to a boil, and then remove from heat.

Step 9

Remove hot jars from canner and fill jars with preserves, leaving ¼ inch of headspace. Remove trapped air bubbles, wipe rims with a damp cloth, and put on lids and screw bands, tightening bands only to “fingertip tight” (until resistance is met, and then just the tiniest bit more).

Step 10

Place jars in the hot water, on the rack inside the canner. (Make sure jars are upright, not touching each other or the sides of the canner, and are covered with at least 1-2 inches of water). Place the lid on the canner, return the canner to a rolling boil, and boil for 10 minutes. (Add 1 minute additional processing time for every 1000 feet above sea level.)

Step 11

Turn off heat and allow canner and jars to sit for 5 minutes. Then remove jars from canner.

Step 12

Allow jars to cool undisturbed for 12 to 24 hours. Then confirm that jars have sealed. Remove screw bands from sealed jars, rinse off outside of jars if necessary, label jars, and store for later use.