Cut off the peel of a lemon. (Be careful not to cut into the white pith just below the zest.) Try to cut large pieces to make it easier to remove them from the lemon syrup mixture later.

Add 2 cups water and sugar to a saucepan; stir. Drop in the lemon peel.

Bring to a boil, and then reduce the heat to low and simmer for 5 minutes.

Remove from heat and let cool completely. Then remove the lemon peel.

Add the lemon juice and sparkling water to the cooled lemon syrup and gently mix. Pour into an ice cream freezer and freeze, following the manufacturer's instructions.