Preheat the oven to 350°F (175°C).

In a mixing bowl, sift together the cake flour and half of the sugar (1/2 cup).

In a separate bowl, beat the egg whites until foamy, then add the cream of tartar and salt.

Continue beating until soft peaks form, then gradually add the remaining sugar (1/2 cup) while beating until stiff peaks form.

Gently fold in the flour mixture and vanilla extract until just combined.

Pour the batter into an ungreased tube pan and smooth the top.

Bake for 30-35 minutes, or until the cake is golden and springs back when lightly touched.

Remove from the oven and invert the pan to cool completely before removing the cake.