For the lemon sorbet, squeeze the lemons and mix with the sweetener and water. Pour into ice cube molds and freeze.
Get the pulp out of the lemon peels and cut off a little at the end so that the lemon peels stand up well. Place the peels in a freezer bag and freeze as well.
After three to four hours, take the lemon ice cubes out of the freezer and place them in a bowl. Crush with a blender or a strong mixer.
Arrange the lemon sorbet in the cold lemon peels.