Potato starch flour, also known as "potato starch," is a key ingredient in Scandinavian baking. Since wheat flour was for a long time a luxury item in Scandinavia, difficult to grow and normally thus imported from warmer climes, Scandinavians depended much more heavily upon the hardier potato starches and flours they could produce locally. Potato starch flour / potato starch is gluten-free (unlike some brands of potato flour, which may contain wheat). A corn-free kosher ingredient, it is also typically used by Jewish cooks in place of flour and cornstarch during Passover.