1 cup water
1 cup sugar
2 - 3 teaspoons lemon zest
1 cup cold water
1 cup fresh lemon juice (about 6 lemons)
1/4 cup limoncello (optional)
Wash and dry lemons. Using a microplane grater, remove the zest from these two lemons until you have about 2 - 3 teaspoons of lemon zest. Place water, zest and sugar into small saucepan and heat until sugar is dissolved. Pour through sieve into ice bath to cool.
Juice the lemons until you have 1 cup of juice. Pour juice through a sieve to remove seeds and pulp. Add juice and 1 cup cold water to cooled sugar mixture. Add 1/4 cup of limoncello and stir 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. Don't over-churn the mixture or else it will be dry and fluffy; it should be a bit soft when you transfer to freezer.