Let the fruit thaw and use the juice that comes out. You can also defrost the fruit in the microwave.
Puree 3/4 of the fruit with a hand blender, then mix with the remaining quarter of the fruit. If you don`t like pieces of jam, you can puree all of the fruit.
Then add the vanilla sugar. Stir in the preserving sugar and let steep for at least 1 hour. Finally add the citric acid. Bring everything to the boil while stirring and let simmer for 4 minutes.
Pour into jam jars, close the jars, turn them over and place on the lid and leave to cool. Tastes sweet and sour in summer.