Preheat oven to 350˚F. Move oven rack to lowest position
In medium bowl stir together flour blend, corn starch, and ¾ c of the sugar. Set aside.
In large mixing bowl, beat egg whites, cream of tartar and salt on medium speed with wire whip attachment until foamy.
Increase speed to high and beat until egg whites have doubled in volume and thickened. About 2 minutes. Beat in remaining 3/4 c sugar a little at a time on high speed, add vanilla with last addition of sugar, until stiff and glossy meringue forms. Do not under beat.
Sprinkle sugar/ flour mixture, 1/4 cup at a time, over meringue, folding in just until mixture disappears, transfer egg white mixture to a very large bowl if necessary.
Spoon into ungreased 10 inch angel food (tube) cake pan. Gently tap pan on counter to remove large air bubbles.
Bake 40 to 45 minutes or until cracks feel dry and top springs back when lightly touched. Do not under bake.
Immediately turn pan upside down onto heatproof bottle or funnel until cake is completely cool, about 2 hours. Run knife or long metal spatula around edge of pan to loosen. Turn cake out onto serving platter. Use long, serrated knife to cut cake
