Preheat your oven to 350 degrees F (170 degrees C) and line two 12 X 9 pans with parchment paper.
In a large bowl, sift together cake flour, sugar, salt, and baking powder.
In another bowl, mix together egg yolks, oil, water, and vanilla flavoring. Then, add the dry mixture to the wet mixture and mix until smooth.
Using an electric mixer, whip egg whites and cream of tartar until frothy. Gradually add sugar and continue beating until stiff peaks form.
Fold the egg white mixture into the wet mixture in three additions. Make sure to incorporate it well without any ribbons of white.
Pour the batter into the prepared pans and bake for 45 minutes or until the tops spring back when lightly pressed. Once done, let the cakes cool completely.