900g prepared plums (washed, cut in half, stone taken out)
900g (ish - I used a little less, in fact) sugar
150 ml water
1 or 2 star anise (I used two but they are quite old. If it's a fresh packet, one would suffice)
Place the prepared plums, the star anise and the water in a preserving (or other large) pan, bring to a boil and simmer for ten minutes or so until the plums are soft.
Remove from the hob and when the simmering has stopped remove the star anise and add the sugar, stirring well. Then just leave it to dissolve, which it will do without any need to stir.
While it's doing that, get your jam jars and sterilise them and put two saucers in the fridge for testing the setting point (if that's the way you test).
Just before you start boiling the jam, pop the sterilised jars into a warm oven (about 120C)
When the sugar has all dissolved and you're ready to start, bring it back to a good boil for about five minutes, then test for set. If it isn't setting, boil again for five minutes. Repeat until setting point is reached, scrape off any scum, then carefully ladle into the hot jars, seal and label.
Mine set the first time - must remember to take the second saucer out of the fridge!