Preheat oven to 375 F. Prepare a 10-inch tube pan, ensuring it is clean and dry so the egg whites don't deflate. Sift together the flour and 1/4 cup of the sugar, set aside. In a large bowl, whip the egg whites, vanilla, cream of tartar and salt to medium stiff peaks. Gradually add the remaining sugar while continuing to whip to stiff peaks.

Fold in the dry ingredients gradually (do not over-mix). Put the batter into the tube pan. Bake for 40 minutes, or until the cake springs back when touched. Cool. Run a knife around the edge of the pan and invert onto a plate. As an option, serve with frosting: beat all frosting ingredients together until smooth and ice the cake.