- BEAT egg whites and vinegar until foamy in a large bowl using an electric mixer. Add icing sugar and mix until combined. Increase speed to high and beat until dense and thick but foamy, about 3 to 7 minutes.
- STIR in 2 to 4 tbsp cold water to thin the icing out to desired consistency. Transfer to a piping bag fitted with a very small plain tip to decorate cooled sugar or gingerbread cookies. If applying silver dragees or other decoration, do so while icing is still wet. Let sit at room temperature until icing hardens.