Measure and mix the cornstarch, potato starch, baking pwder, and xanthan gum in a bowl-set aside.
Beat egg yolks, sugar, vanilla, and water. Blend til very very smooth.
Whip the whites with salt and cream of tartar to form soft peaks.
Fold reserved dry ingredients into yolk mixture fully and then fold in whites until fully combined.
Fill a Ziploc bag with ΒΌ inch cut off corner diagonally to use as a piping bag.(if you have a pastry/piping bag, use that)
Pipe out 3 inch long finger shapes onto a parchment(silpat)lined cookie sheet, allowing room for cookies to spread.
Bake 6-8 minutes or until golden at 375 degrees.
Allow to cool slightly before transferring them to a cooling rack.
I made my ladyfingers longer than 3 inches so this recipe made 24 fingers. If you made them smaller you could make up to 40.