Sift potato flour and baking powder twice. Reserve.
Whisk egg yolks until smooth, and add salt and sugar, and beat again until light.
Whisk the egg whites until they are stiff peaks. Fold the whites into the egg yolk mixture, then fold in the potato flour and baking powder. Stir in the ice water last.
Spoon into paper lined cups and bake until browned and test done, checking around 15 minutes.