This method of making iced green tea is called cold brewing. I personally prefer this method since it's easiest -- all it requires is a bit of forethought.
Recipe Ingredients:
4 cups of cold water
3 tbsp of green tea (I use sencha)
Recipe Steps:
Mix the loose tea in a pitcher of the cold water. Put in the refrigerator for about five hours or overnight is fine, too. Filter before serving and add a few ice cubes.