Limoncello

Wash the lemons thoroughly with a vegetable brush under warm water to remove any wax or residue, then pat them completely dry.
Using a vegetable peeler, carefully remove the zest from the lemons in long strips, avoiding the bitter white pith underneath as much as possible.
Place the lemon zest strips into a large, clean 1-gallon glass jar, then pour the entire bottle of vodka over the zest. Seal the jar tightly.
Store the jar in a cool, dark place for at least 4 weeks, gently shaking the jar once a week. The vodka will turn a deep, vibrant yellow.
After 4 weeks, combine the sugar and water in a medium saucepan over medium heat. Cook, stirring frequently, until the sugar fully dissolves to create a simple syrup, then remove from heat and let it cool completely.
Strain the lemon-infused vodka through a fine-mesh sieve into a large bowl, pressing on the zest to extract all the flavorful oil, then discard the spent zest.
Stir the cooled simple syrup into the strained limoncello until well combined, then use a funnel to pour the mixture into clean bottles.
Seal the bottles and store the limoncello in the freezer for at least 4 hours, or until ice-cold, before serving.