Sift the flour 3 times into a bowl. Sifting is important because otherwise the cake will not be fluffy and soft. In a large bowl, beat the egg whites very stiffly, adding tartaric acid, vanilla sugar and gradually adding the sugar; Finally stir in the bitter almond flavor. Carefully fold in the flour with a whisk (never use the mixer!).
Pour the dough into a large, greased and floured springform pan and bake for 45-50 minutes. Let the mold cool down a little and turn it upside down until it is completely cool; Remove the cake only after it has cooled down completely.
If you want, you can puree a few strawberries with sugar and lemon juice and serve as a sauce.
In America there are special baking molds for this, unfortunately these are very expensive, a springform pan with a tube base is suitable as a replacement. However, I baked it in a springform pan like a sponge cake.