Combine sugar, water, and cream of tartar in a saucepan. Cook until candy thermometer reaches 238 degrees F. Or until the syrup spins a long thread when dripped from spoon. Beat egg whites until stiff. Pour a thin, slow stream of the syrup into the egg whites, beating constantly until frosting stands in peaks. Stir in salt and vanilla to taste. Frost quickly as the frosting sets up. |