Limoncello is an Italian liqueur. It has a very smooth, sweet taste to it with of course a bright and intense lemon flavor. It is typically made with vodka as its base liquor and is often sipped on its own or mixed with a tonic water or club soda for a refreshing and light cocktail. You can even make your own by steeping lemon zest in vodka and then adding simple syrup. The longer it sits and ages, the better it is.