Break the eggs and beat them with the sugar (no need to beat too much or use a mixer).
Add the oil, sifted flour and the yoghurt to which you've added the baking soda. Stir.
Add the vanilla and crumbled walnuts. Stir again.
Smear the cake form in which you'll be baking with oil (or butter).
Pour in the mixture. Even it out and bake in a preheated 356°F (180 °C) until ready, while checking with a wooden skewer.
Take the ready cake out of the oven, invert it onto a platter and leave to cool a bit.
Carefully remove the form and sprinkle generously with powdered sugar.