Take 250 ml of milk, heat it a little and pour it into a bowl. Add 25 g of fresh yeast (or 10 g of dry yeast if you prefer). Stir well until the yeast is completely dissolved. Add 250 g of sifted flour, mix, add vinegar, mix again. Close the bowl and place it in a warm place for 30 minutes to allow the dough to rise.
Divide 3 eggs into whites and yolks at the same time. Add sugar and vanilla to the yolks, beat until smooth. Beat the egg whites with salt until stiff peaks form.
First add the egg and sugar mixture to the yeast sourdough, mix.
Then add 100 g of soft butter, previously softened in the microwave, to the dough.
Next, gently introduce the egg whites.
Gradually add the rest of the flour, the amount of which may vary depending on the moisture content of the flour and the size of the eggs. Transfer the dough to the counter, knead, add flour if necessary, but don’t overdo it. The dough should be soft and slightly sticky. Return to the bowl, cover, and let sit warm for 1 hour.
Continued on the next page