Preheat oven to 180 C / Gas 4. Sieve flour, cornflour and icing sugar together 5 times and set aside.
In a large clean bowl, beat egg whites with 1 pinch of salt until foamy. Add cream of tartar and continue beating until soft peaks form. Gradually add sugar while beating and continue to beat until very stiff. Add vanilla.
Quickly fold in flour mixture. Pour into a 26cm tube cake tin.