Combine dried egg whites (or meringue powder), water, cream of tartar and lemon (or almond) extract in a large bowl. Add sugar and beat with an electric mixer on medium speed until stiff peaks form, 6 to 12 minutes.Advertisement
Add water if needed to adjust icing consistency for piping or spreading. Add food coloring, if desired. Keep a damp cloth or paper towel directly on the icing while you work, to keep it from drying out.
Make Ahead Tip: If not using immediately, cover icing with a damp cloth and plastic wrap and store in the refrigerator for up to 3 days. Beat again before using.