NOTE: Plan ahead- prepared plums need to be refrigerated overnight!

Cut each plum into quarters: remove/discard pits. Put plums into large bowl. Add sugar and lemon juice; stir well, to combine. Cover bowl with plastic wrap, and place in refrigerator. Refrigerate overnight or at least 8 hours for best results.

Before you cook the plums, place a small plate into your freezer. NOTE: You will use freezing cold plate to test jam for doneness later, so this is an important step!

Pour refrigerated plums into medium-sized saucepan. Turn to MEDIUM eat; bring mixture to a boil. Once boiling, continue cooking plums for 2 minutes, stirring often. Turn heat down to LOW. Continue to cook, stirring often, for 15- 20 minutes (plums will turn red). Skim off/discard white foam that rises to surface,

To see if jam is ready, remove plate from freezer. Put a teaspoon of hot jam on plate. If jam "sets up" within first minute, jam is ready. If jam is too runny, put plate back in freezer; continue to cook jam 2-4 more minutes. Try again, and once jam will set up, it's ready. Remove saucepan from the heat.

Canning jars and lids need to be clean, sterilized and hot, following recommended USDA guidelines for safe canning. This small batch will yield approx. 3 cups ( about 3 half pint jars), but you can easily double or triple recipe.

Spoon or pour jam (using a a canning funnel) into sterilized jars, leaving a headspace of 1/8". Use a plastic utensil to remove air bubbles in jars, then wipe rims of jars clean with a damp towel. Attach prepared flat lids and add screw bands; tighten to fingertip tightness. Process jam (in boiling water at least 1" above top of jars) in a water bath canner for 10 minutes.

Remove jars with tongs; place on a dish towel on counter. NOTE: Do not place boiling hot jars directly on countertop because temperature variations could cause jars to crack. Let jars sit undisturbed for about 12 hours. Jam will thicken as it cools, and jars should seal; (you hear a pinging sound as they seal). If sealed correctly, lids should have no give when tested by gently pressing down on the lid with a finger after jam cools. Any jars that don't seal should be refrigerated. Label sealed jars; store in pantry. After opening jar, keep refrigerated.