Core and quarter the plums. Peel and core the apples and pears, then cut into small pieces. Add the lemon juice and the preserving sugar. Crush everything in a blender or with a hand blender until you have the desired mass, depending on whether you like it lumpy or without pieces. Bring the prepared ingredients to the boil in a large saucepan with a pinch of cinnamon and cook for about five minutes, stirring constantly. Then immediately pour the jam into jars, close the jars and turn them upside down to cool.
The amount of fruit is variable, the main thing is that the plums, apples and pears are used in approximately the same proportion. The preserving sugar must be adjusted accordingly. The jam will be relatively sweet. Those who like it less sweet should just use a little less sugar or a 2: 1 preserving sugar.