For the cherry-strawberry-raspberry jam, place strawberries, cherries and raspberries in a large saucepan, mix with preserving sugar and let marinate for a few hours.
Blend with a hand blender, bring to a boil and simmer for 5 minutes until bubbly. Add lemon juice and rum, bring to a boil again.
Pour the cherry-strawberry-raspberry jam into sterile jars and seal immediately.
Preparation Tip:
The cherry-strawberry-raspberry jam can also be made without rum.