In medium mixing bowl, mix the ingredients in order with a spoon until well incorporated. The glaze may be lumpy rather than smooth at this point, do not worry.
Let the glaze sit for one hour to give the lumps of sugar time to dissolve and any air bubbles to rise to the surface. A good glaze is somewhat thick, a little goopy, sort of stretchy and still a little soupy. If it appears too thin and watery, add 2 Tbsp. of powdered sugar. And if it is too pasty, add a little extra warm water.
After the hour has passed, stir well enough until smooth. The consistency should be thick, but still thin enough to disappear after 10 seconds when it is folded over onto itself.