Wash the lemons.
Take a vegetable peeler and carefully remove long strips of the lemon peel without taking a lot of the pith (white part). Peeling the lemons is the most important part of making homemade limoncello. You DO NOT want to infuse the alcohol with lemon peels that still have some pith because it will make your limoncello bitter. So if the lemon peel has white on it, carefully remove it with a knife.
Pour the alcohol into a large container with a sealed lid. Add the lemon peel and stir.
Place the sealed container in a dark and cool space. Let the mixture infuse for at least two weeks. There are two signs to look for to know when the mixture is ready. One, when the lemon peel is white and easily snaps into two pieces when bent. Two, the liquor has turned yellow.
Once the mixture is ready, make a simple syrup. Mix the sugar and water in a medium saucepan. Then bring the mixture to a boil. Once all of the sugar has dissolved, turn off the heat and cool down the simple syrup.
While the simple syrup is cooling down, remove the lemon peel from the infusion. Then take a cheesecloth and fold it to create two layers. Pour the infusion through the cheesecloth with a funnel and into a bottle or another container.
Pour the simple syrup into the infusion and mix.
Seal the container and place it back in a dark and cool place for another two weeks.
Pour the homemade limoncello into a bottle with a screw top (I like to reuse the Everclear bottle - remember this recipe makes two 750ml bottles).
Store the bottled limoncello in the freezer and serve chilled.