Lemon yogurt sponge cake: how to make this amazing dessert

Ingredients:
4 yolks
8 g vanillin
30g sunflower oil
The zest of a lemon
300g Greek yogurt
50g flour
30g cornstarch
4 egg whites + 1 pinch of salt
1 teaspoon lemon juice
80g sugar
Icing:
75 g icing sugar
3-4 teaspoons lemon juice

Directions:

1. First mix the egg yolks with the vanilla, oil, yoghurt and lemon zest. Form a creamy and homogeneous mixture. Then add the flour and cornstarch.
2. Separately whisk egg whites with salt and gradually add sugar and lemon juice.
3. Combine the two pastes and mix well.
4. Pour everything into an 18 cm diameter mould.
5. Place the mold in another pan and fill it with hot water.
6. Bake at 160 degrees for 60-70 minutes.