Make a simple syrup by boiling sugar and water together for five minutes. Cool and place in a covered container with six or eight sprigs of fresh mint, then refrigerate overnight.

Make one julep at a time by filling a julep cup with crushed ice, adding one tablespoon mint syrup and two ounces of whiskey. Stir rapidly with a spoon to frost the outside of the cup. Garnish with a sprig of fresh mint.