Peel the zest off the lemons, making sure that you leave as much of the pith (the white layer below the zest) as you can behind. Place the lemon zest in a mason jar in which you will have poured the alcohol. Close tightly and put the jar in a cool, dark place for 3 or 4 days to infuse.

Once the infusion is done, heat the sugar and water over a high flame until the sugar has entirely melted and the water is just about to boil. Turn off the heat and let the resulting syrup cool completely.

Filter the infused alcohol through a sieve lined with cheesecloth into the syrup. Then pour the mixture into a decanter or bottle. Let the mixture rest for about a week before using.