5-6 Etrogs (citrons)
1 (750 ml) bottle 100-proof vodka*
1 vanilla bean
2 cups sugar
2 1/2 cups water
* Use 100-proof vodka, which has less flavor than a lower proof one. It also keeps the finished liquor from being too sweet and the high alcohol content ensures that the liquor will not turn to ice in the freezer.
Wash the etrogs with a vegetable brush and hot water to remove any reside of pesticides or wax. Pat them dry.
Pour 1/2 the vodka into a large glass jar with the vanilla bean. Carefully zest the lemons with a zester or vegetable peeler so there is no white pith on the peel. Use only the outer part of the rind. The pith, the white part underneath the rind, is too bitter and would spoil your liquor. Add the lemon zest directly to the jar as it is zested.
Cover the jar and let sit at room temperature for at least ten days and up to forty days in a cool dark place. The longer it rests, the better the taste will be. As it sits, the vodka will slowly take on the flavor and rich yellow color of the zest.
In a large saucepan, combine the sugar and water. Cook until thickened, approximately 5 to 7 minutes. Let the syrup cool before adding it to the vodka mixture. Once the syrup is cool pour it into the jar with the vodka. Add the remaining vodka. Allow to rest for another ten to forty days.
After the liquor has rested for the second time strain the mixture, discarding the lemon zest and vanilla bean. Pour into bottles. The liquor is best served chilled, so store it in the freezer until ready to use. It will keep fine at room temperature as well, but should be chilled before drinking.