Zest the lemon with a vegetable peeler to get long thin strips. Trim any white pith with a pairing knife and discard.

Pour the vodka over the lemon peel in a large pitcher or container. Cover or seal the container and allow mixture to stand at room temperature for four days. You can steep the peels for up to a month.

When done steeping make a simple syrup by combining the sugar and water in a saucepan over medium heat and stirring until sugar is dissolved. This may be about 5 minutes.

Allow the simple syrup to cool completely and then add to the vodka mixture. Let sit overnight at room temperature.

Strain the the mixture through a fine sieve and discard the solids. Transfer limoncello to clean bottles using a funnel. Seal and refrigerate at least 4 hours.

Store limoncello in the freezer for up to a year. Serve in chilled shot glasses.