Prepare a yeast dough from the ingredients for the pre-dough and let it rise for 1 hour. The dough is still very runny!
Then add the 250 g flour and knead well. Let the main dough rise for another hour.
Grease a baking sheet (drip pan) and spread the dough onto it after kneading again briefly. Sprinkle with sugar immediately.
Mix the sour cream with 1 teaspoon sugar. Spread about 18 small mountains of sour cream on the dough with a teaspoon. Let rest for about 15 minutes.
Bake in a preheated oven at 180 ° C top / bottom heat for about 15 minutes. Tip: Put the cake under the grill for a few more minutes to brown the surface really nicely. But be careful - stop by and look.
Sprinkle with sugar again immediately after baking.