Preheat oven to 375°F and have an ungreased tube pan ready.

Sift together half of the sugar, flour, and salt 5 times. Set aside.

Whip egg whites until frothy, then add cream of tartar and vanilla extract.

Gradually add remaining sugar while whipping until stiff peaks form.

Gently fold in the flour mixture into the egg whites.

Pour batter into the pan, smooth the top, and remove air bubbles.

Bake until golden and a toothpick comes out clean.

Invert the cake to cool once out of the oven, then remove from the pan.