Bring to boil the water and sugar to make a simple syrup. Add the zest of one lemon. You can use a potato peeler, it doesn’t need to be grated finely. Let cool completely and remove the lemon peel.
In a freezer safe bowl with a lid, add limoncello, simple syrup, sour cream, the juice of the zested lemon, and salt. Mix well and freeze for 4 hours stirring well after 2 hours.
Serve topped with fresh raspberries.
Notes
If you freeze it overnight it will have an ice cream consistency which is nice too.It will never freeze completely solid because of the liquor which makes it even better.