Sift flour with 3/4 cups sugar 3 times; set aside.
In a large bowl beat egg whites and salt with electric mixer until foamy. Add cream of tartar and beat until soft peaks form. Gradually beat in remaining 1 cup sugar, sprinkling 1/4 mixture at a time, beating well after each addition until soft peaks form when beater is withdrawn.
With a large rubber scraper gently fold in vanilla.
Gently fold in 1/4 of flour mixture at a time over egg whites with an over and under motion after each addition. Fold additional 10 strokes after last addition until flour is well blended.
Gently transfer batter to ungreased pan. With a spatula or knife, cut through batter gently.
Bake on lower rack for 55-60 minutes or until top is browned and cake tester comes out clean.
Invert pan on counter to cool cake thoroughly (about 2 hours). Loosen cake with spatula from pan; remove from pan.