Put the sugar and lemon peel in a saucepan with 2 cups water. Bring to a boil just 5 minutes. Remove from the heat, and cool. Store the syrup in a glass jar in the refrigerator.
Put 1 tablespoon of lemon syrup in a glass with a few ice cubes and a sprig of fresh mint. Squeeze in the juice of half a lemon. Stir in cold water, to taste. Sweeten with more syrup, if you like.