A basic plum jam recipe to use up a glut of plums.
a knob of butter
Stone and half all the plums. A rather therapeutic exercise if you are a patient person and have radio on.
Put in a big pot with a dash of water (1 tbsp) and boil for 20 mins or so, until the plums are very soft and skin comes off easily when you pick them.
Add sugar and stir to make sure it all dissolves. Turn up the heat and let the mixture comes to a rolling boil. Boil for 5 to 10 minutes, or until it's set. *
Stir in the knob of butter and the scum on top will magically disappear! Leaving you with jewel red jam.
*To test if jam is set: Put a small dish in the freezer, spoon a little bit of jam onto the cold dish, wait for 20 sec or so, push the jam with a finger and if it wrinkles, your jam is set!