Bring water with sugar to a boil, lightly bubble for 2 min, cool and add juice of one lemon (if berries are not very sour, add 2 tb, otherwise less). Crush the berries with the syrup and strain through a sieve.
Note: the amount of sugar – 100 g – is a guide ! If necessary, add powdered sugar after pureeing. The mixture must taste very sweet !
Freeze in the freezer.