Put the zest of 10 fresh lemons in a large pitcher, cover with 1 bottle (750ml) of vodka of your choice. Let this steep for 2 weeks at room temperature.
Add 2½ cups of sugar to 3 cups of water and heat in a saucepan until dissolved. Turn off heat, and once cool, pour the syrup over the vodka mixture.
Cover and let stand overnight. Strain the mixture and discard the zest. Refrigerate until cold and enjoy.