(Adapted from Sure-Jell recipe)
7 cups pitted and finely diced plums, peels left on (buy about 4 pounds of ripe plums and eat any extras)
1/2 cup water
4-1/2 cups sugar, divided
1 box low sugar/no sugar powdered pectin
1. Bring canner, half full with water, to simmer. Wash eight 8-ounce jars and screw bands in dishwasher to sterilize. Leave in dishwasher until ready to use. Place flat lids in small saucepan, cover with water, and bring to a gentle simmer. Turn off heat and let stand in hot water until ready to use.
2. Take 1/4 cup of the sugar and mix with the pectin in a separate small bowl. Set aside.
3. Pit unpeeled plums. Finely chop fruit. Place fruit in saucepan and add water. Bring to boil. Reduce heat to medium-low. Simmer for 5-10 minutes (until they look soft and cooked), stirring occasionally and mash a bit with a potato masher. Measure exactly 6-1/2 cups prepared fruit into a heavy-bottomed stockpot.
4. Add pectin/sugar mixture to fruit in stock pot. Bring to full rolling boil (a boil that doesn’t stop bubbling when stirred) on high heat, stirring constantly. Stir in remaining 4-1/4 cups sugar. Return to full rolling boil and boil exactly 1 minute, stirring constantly. Remove from heat. Let sit for 2 minutes, stirring occasionally and skimming off any foam with a metal spoon.
(Save the foam! It is delicious. Put it in the refrigerator and use it within a few days. Stir it into your yogurt, put it on your ice cream, or just use it like jam. It is jam really, just foamier.)
5. Ladle into prepared jars, filling to within 1/8 inch of tops. Run a butter knife around inside of jars to remove air pockets. Wipe jar rims and threads. Cover with lids. Screw bands on tightly. Place jars on rack in canner. Water must cover jars by 1 to 2 inches. Add boiling water, if necessary. Cover and bring water to gentle boil. Process for 10 minutes.
6. Remove jars and place upright on a towel to cool completely. After jars cool, check seals by pressing middles of lids with finger. (If lids spring back, lids are not sealed and refrigeration is necessary.)