Heat oven to 375F. Stir together flour and half of the sugar. Set aside.
In a large mixing bowl, beat egg whites and salt until foamy. Add the other half of white sugar 2 tablespoons at a time while beating. Beat until stiff peaks form. Beat in vanilla extract. Gently fold in sugar/flour mixture a bit at a time until flour sugar mixture disappears. Push batter into un-greased tube pan (10 x 4 inches) and spread evenly. Bake for 30-35 minutes or until top springs back when touched lightly with finger. Invert tube pan on funnel. Let hang until cake is completely cool.
