The plums have really been amazing this summer, and I've enjoyed sampling a wide variety of them. As an avid canner, I've also experimented with many different flavor combos. This one preserves the plums summery'ness while helping usher us into fall. Delicious! —em-i-lis
Set up your canning pot, get the water heating and the jars sterilizing. Mix the plums and sugar in a non-reactive bowl and let sit 5-10 minutes.
In a heavy-bottomed pot set over medium heat, put the fruit-sugar mixture. Stir consistently until the sugar has melted completely, about 5 minutes. Add in the remaining ingredients and stir to combine.
Turn up the heat to medium-high, and stir/cook until the fruit starts falling apart and you’ve got a solid amount of juice surrounding it. You want to have it at a good boil!
The jam should start thickening after 15 minutes, and at about 20 minutes, either test the temperature (you’re looking for 217-218) or remove the plate from the freezer and dab about 1/4 tsp on it. If the jam firms up quickly, you’re ready to can. If not, cook/stir for a couple more minutes.
When your jam is done, ladle it carefully into your jars, slide a thin knife or chopstick or the like along the inside edges of the jar to let any air bubbles in the jam escape, screw on the lids and bands and process for 12-15 minutes. Then, remove the jars from your waterbath and set them aside to cool on a cooling rack covered with a dishtowel (to prevent slippage).