Under 30 Minutes
Beat water and meringue powder with a mixer on medium speed until soft peaks form, about 3 minutes. Add sugar, and beat until icing holds a ribbonlike trail on the surface for 5 seconds when beater is raised.
Tint icing with food coloring just before using. (If making poppy-shaped lemon cookies, divide icing before tinting.)
SourceMartha Stewart Living, April 2010