It's done! After 40 days or so of lemon peel infusing the limoncello was ready for the last few steps. To test if the infusion is ready, fish out a large lemon peel. If it breaks like a potato chip it is done, if not check back in a few days.
Strain peels from liquid. Combine lemon infused alcohol with simple syrup. It will turn cloudy and will be ready to be enjoyed over ice and stored in the freezer.
4 cups white sugar
4 cups water
Combine water and sugar in a pot on the stove. Heat and stir until mixture becomes clear and sugar has dissolved. Remove from heat and cool to room temperature.