Homemade traditional Christmas gingerbread cookies with icing ornate. Gingerbread Man. angel. bell on ceramic plate with xmas decorations over dark background.. (Photo by: Natasha Breen/REDA&CO/Universal Images Group via Getty Images)
For The Best Royal Icing, Use Powdered Sugar With Tapioca Starch
Royal icing, often used as a sugary mortar to hold gingerbread houses together, tends to taste chalky due to the powdered sugar. To improve the taste, add tapioca starch.
Tapioca starch prevents the finely ground sugar from clumping just like cornstarch does, but has qualities that eliminate the chalky taste and mouthfeel.
Tapioca is nearly flavorless and has a slight sweetness that enhances the icing. As opposed to cornstarch, tapioca absorbs water more easily and creates a shiny finish.
Since the price is higher than standard powdered sugar, use tapioca starch sugar for recipes when the powdered sugar is a major component, like royal icing.