Wash, clean and halve the strawberries. Wash and clean the rhubarb and cut it diagonally into 1 cm wide pieces. Grease a springform pan (26 cm Ø) and dust with flour. Preheat the oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer).
Cream 175 g butter, 175 g sugar, vanilla sugar and 1 pinch of salt with the whisks of the mixer. Stir in the eggs one by one. Mix 275 g flour and baking powder and stir in alternately with the yoghurt.
Fill the dough into the mould and spread it smooth. Mix strawberries, rhubarb and 1 tbsp. sugar. Put half of the fruits on the dough and press in about 1 cm deep. Spread the remaining fruit on the cake. Bake in a hot oven for 45-55 minutes.
Remove the cake from the oven, remove from the edge of the tin and allow to cool. Remove yoghurt cake from the mould. Dust with icing sugar.