Wash the lemons thoroughly under warm water to remove any wax or dirt. Dry them completely with a clean towel.

Using a vegetable peeler, carefully peel the lemons, avoiding the bitter white pith as much as possible.

Place the lemon peels in a large glass jar and pour the vodka over them. Seal the jar tightly.

Store the jar in a cool, dark place for 4-7 days, shaking gently once a day. The longer it infuses, the stronger the lemon flavor.

After infusing, prepare the simple syrup: In a saucepan, combine water and sugar. Heat until the sugar dissolves completely, then let it cool.

Strain the lemon-infused vodka into a large bowl, discarding the peels. Mix in the cooled simple syrup.

Bottle the limoncello in clean glass bottles and store in the freezer for at least 4 hours before serving.