Beat the egg yolks with the sugar until pale and light. Add the flour and beat well. Slowly pour over the vegetable oil, cocoa and yogurt. Whisk the egg whites with pinch of salt until stiff but not dry and fold into the mixture.

Butter a 20 cm. round cake pan. Pour the batter into the prepared pan and bake for about 45 minutes or until the cake is done (until a tester inserted comes out clean and dry).

Let it cool. Sprinkly lavishly with sifted icing sugar before serving.