Add eggs (3 PCs.) to the sourdough, add salt (1 teaspoon), Add melted and cooled to room temperature butter, add 10 g of vanilla sugar. Beat the mixture with a whisk. Then gradually add the remaining flour in portions. Knead a soft dough. Cover the container with the dough with food wrap or a towel and put it to rise. After the first rise, knead the dough and put it to rise again. Then you can start forming the rolls.