If you are lucky enough to find them, get your hot little hands on some Damson plums. They are small and sour when fresh, but make the absolute best plum jam in the world. I have listed two different options for amounts of sugar/water in the recipe. The lower amounts will make a soft, very tart jam. That's the way I like it. With more sugar and water (keep them in proportion) you will get a more traditional jam, firmer and sweeter. I like it that way, too, I have to admit. Unfortunately, Damsons are clingstone and can't be pitted before the cooking starts. I have burnt myself quite badly a few times making this jam, while fishing out pits from the boiling pot, but this year (2004) I have figured out how to avoid that and have updated the recipe.
- Wash and pick over the plums.
- Combine the plums and the water.
- Bring to a boil and cook 15 minutes, stirring constantly.
- Allow to cool enough to handle - or completely, if you like - and fish out the pits (I put them through a food mill, and then removed the pits from the remaining pulp).
- Return the pulp to the rest of the jam once the pits are out.
- Meanwhile, put the jars into a canning kettle and cover with water to one inch above the tops of the jars.
- Bring to a boil, boil 10 minutes to sterilize.
- Return the plums to the jam kettle, and bring them back to the boil. Add the sugar to the plums, stirring to dissolve.
- Boil to jam stage, about 20 minutes. Test for the gelling point with one of the following methods: Temperature test — Use a jelly or candy thermometer, and boil until mixture reaches the following temperatures at altitudes of: Sea level to 1,000 feet — 104°C/220°F; 1,001 feet to 2,000 feet — 103°C/218°F
- Sheet or spoon test — Dip a cool metal spoon into the boiling jelly mixture. Raise the spoon out of the steam, about 12 inches above the pan. Turn the spoon so the liquid runs off the side. The jelly is done when the syrup forms two drops that flow together and sheet or hang off the edge of the spoon.
- I like the"sheet" test.
- As the jam cooks, remove any pits you may have missed.
- Remove from the heat and stir and skim 5 minutes.
- Pour into hot sterilized jars and seal with lids sterilized according to the manufacturers directions.
- (Generally, boiled for 5 minutes.) Place jars of jam back in boiling water bath and boil for 5 minutes.
- Let cool, and store when the jars have sealed.