When making plum jam either the plums can be halved and stones removed before cooking or you can remove them with a slotted spoon while it’s boiling (they float to the top). If the stones come away easily I would recommend doing that…the other way can take ages.
1 kg plums
1 kg sugar
250 mls water
Wash the plums and de-stalk if necessary. Sterilise jars by heating in a slow oven for 1/2 hour at least. If using metals lids sterilise these by boiling in water for 10 minutes.
Put plums in a large pot with the water and cook about 30 – 45 minutes (lid on) till pulpy. Stir in sugar and boil gently until thickened and test a little in a saucer in the fridge, if it comes out with a skin on top it will set. Makes around 7 – 8 smallish – med jars.