One of my favourite jams, perfect for use in cakes, desserts and slices, and delicious on toast, or brioche.
Wash and halve and stone the plums.
Cut the plum halves into four pieces.
Combine plums, raspberries and lemon juice in a preserving pan or large heavy based saucepan.
Cover with a lid and place over very low heat until the juices begin to run.
Gradually increase the heat until simmering, and cook gently, covered for 15-20 minutes, until the fruit is tender.
Bring to the boil and boil rapidly, uncovered, and stirring at regular intervals to prevent the jam from catching on the bottom of the pan, until setting point is reached, approximately 15 minutes.
Carefully pour into warm, sterilised jars and seal.