1/2 cup water
3/4 cup sugar
1 tablespoon lime zest
10 - 12 ripe kiwis
juice of 2 limes
1/4 cup limoncello (optional)
Wash and dry the limes. Using a microplane grater, remove the zest from the limes until you have about 1 tablespoon of zest. Place water, zest and sugar into small saucepan and boil gently for 10 minutes to reduce mixture and extract lime.
Peel the kiwis and remove the hard ends and even the whitish core, if desired. Place kiwis in blender. Juice 1 - 2 limes and add to blender. There's plenty of lime flavor from the zest, so avoid the temptation to add a lot of juice. Pour in the reduced lime syrup and purée the mixture just until smooth (too much and the seeds will start to break down). Pour the purée into a sieve or chinois and gently filter out lime zest and kiwi seeds. Pour this into ice bath and stir in 1/4 cup of limoncello until blended. Chill mixture in ice bath until less than 45° F. Pour into ice cream maker and freeze according to your maker's instructions.
Once chilled, remove from ice cream maker and place in dedicated (odor-free) container to let ripen in the freezer for several hours. Because of the alcohol, it will always be a tiny bit soft.