Wash the lemons thoroughly and pat them dry. Using a vegetable peeler, remove the lemon zest in wide strips, avoiding as much of the white pith as possible since it can add bitterness.

Place the lemon peels in a large glass jar with a tight-fitting lid.

Pour the vodka or grain alcohol over the peels, ensuring they are fully submerged. Seal the jar and store it in a cool, dark place.

Let the mixture infuse for 7 to 14 days, gently shaking the jar every couple of days. The alcohol will gradually turn a bright yellow color as it absorbs the lemon oils.

After the infusion period, prepare the simple syrup by heating water and sugar in a saucepan over medium heat. Stir until the sugar completely dissolves, then allow the syrup to cool to room temperature.

Strain the lemon peels from the infused alcohol using a fine mesh strainer or cheesecloth.

Combine the infused alcohol with the cooled simple syrup and stir well.

Pour the limoncello into clean glass bottles, seal them, and refrigerate or freeze for at least 4 hours before serving.

Serve very cold in small glasses as a refreshing after-dinner drink.