Make sure that the lemons are scrubbed to remove any waxy residue from pesticides. If you are able to get organic ones , this would be the best option.
Zest your lemons, making sure to use only the yellow outer skin. If you go too deep and take the pith it will cloud your limoncello and it will be bitter.
Pour the bottle of vodka into a airtight container and add the zest. Seal the jar and place in a dark cupboard
Allow this to sit for a minimum of 10 days. I like to leave mine for at least one month,but preferably three. During this time all the essential oils from the lemon are released.