Using a vegetable peeler or small knife, remove the peel from the lemons in very thin strips. Try to get just the lemon peel and not the white pith. If you do get pith, trim it away.
Place the lemon peels and all of the vodka in a Vitamix or blender and process until the peel is finely ground. About 25 – 30 seconds.
Pour the mixture into a two-quart jar or pitcher and cover with a lid or plastic wrap. Store in a cool, dark place about room temperature for one week. Give the jar a shake every couple of days to mix up the zest.
Strain the limoncello through a fine mesh strainer lined with cheesecloth into a clean bowl. Press on the solids to remove as much liquid as possible. Discard the zest. Transfer to a clean pitcher.
Add water and sugar to a large saucepan over medium heat. Stir often until the sugar dissolves, about 5 minutes. Cool completely.
Add sugar water to lemon infused vodka and stir to combine. Refrigerate until ready to serve.
Or transfer limoncello to bottles; seal and refrigerate until cold. Four hours to overnight.
Notes
Notes: Limoncello can be refrigerated for up to one year or kept in the freezer for two years. Gently shake before using.One ounce serving.