In medium bowl, stir together powdered sugar and meringue powder. Stir in 5 teaspoons lemon juice and enough of the 4 to 5 tablespoons water to make a thin icing. Transfer 1/2 cup of the icing into small bowl; set aside. Using a flexible pastry brush
, paint cookies to the edges with icing. Place on wire rack to dry completely, about 30 minutes.