Preheat your oven to 350°F (175°C).
In a mixing bowl, beat the egg whites until foamy.
Add the cream of tartar and salt, continuing to beat until soft peaks form.
Gradually add half of the sugar, beating until stiff peaks form.
Sift together the flour and remaining sugar in a separate bowl.
Gently fold the flour mixture into the egg whites, using a spatula.
Add vanilla extract and fold it in carefully.
Pour the batter into an ungreased angel food cake pan.
Bake for 35-40 minutes or until the cake is golden brown.
Invert the pan onto a wire rack to cool completely before removing.