Preheat the oven to 350°. Sift the sugar 3 times into a mixing bowl. In a separate mixing bowl, sift the flour 5 times. Mix 1/3 cup of the sugar with the flour.

With an electric mixer, beat the egg whites until foamy. Add the cream of tartar and salt and continue beating. As the whites begin to stiffen, gradually add the remaining sugar and continue whipping until the whites form stiff glassy peaks. Add the vanilla and beat for 1 to 2 seconds. With a rubber spatula, gently fold in the flour, ¼ cup at a time.

Pour the cake batter into the pan and bake for 40 minutes.

Invert the pan on a rack to cool, leaving at least 1 inch air space between the rack and the table. (You might want to “hang” the pan over the neck of a tall bottle to accomplish this.)

When completely cooled, pull the sides away from the pan with a fork and unmold the cake.