Sift the icing sugar into a bowl. Add a few drops of flavoring, if you like.
Using a wooden spoon, gradually stir in enough water until the mixture is the consistency of thick cream. Beat until white and smooth and thick enough to coat the back of the spoon. Mix in some coloring, if you like, and use immediately.
Flavour variations:
Orange or lemon: Replace the water with strained orange or lemon juice.
Chocolate: Sift 2 tsp cocoa powder into the icing sugar.
