Place A Rack In The Center Of The Oven, And Preheat The Oven To 350°F.
Set Aside An Ungreased 10″ Tube Or Angel Food Pan.
Sift The Flour 4 Times In A Large Mixing Bowl.
The Last Time, Sift The Cream Of Tartar Along With The Flour.
Set This Mixture Aside.
Place The Egg Whites In A Large Mixing Bowl, And Beat With An Electric Mixer On High Speed Until They Are A Stiff Froth, 4 To 5 Minutes.
Add The Sugar, 2 Tablespoons At A Time, While Beating For 4 To 5 Minutes More, Until Stiff And Glossy.
Beat In The Vanilla And Salt.
Gently Fold In The Flour Mixture With A Rubber Spatula, Just Until Combined.
Turn The Batter Into The Reserved Pan.
Smooth The Top With The Spatula, And Place The Pan In The Oven.
Bake The Cake Until It Is Lightly Browned And Springs Back When Lightly Pressed, 30 To 35 Minutes.
Remove The Cake From The Oven And Immediately Turn It Upside Down On A Wire Rack So The Cake Cools Upside Down For 1 Hour.
When Ready To Serve, Turn The Pan Right Side Up And Run A Long, Sharp Knife Around The Edges.
Give The Cake A Gentle Shake To Loosen It From The Pan.
Invert It Onto A Plate Or Rack, Then Invert Again So The Cake Is Right Side Up.
Slice And Serve.
