Mix yeast with 5 tablespoons of lukewarm butter milk. Put the flour into a bowl, make a depression in the middle and add the yeast milk. Cover and leave to rise in a warm place for about 15 minutes.
Add the remaining buttermilk (it should be at room temperature) and 2 teaspoons of salt to the pre-dough and knead with the dough hooks of the hand mixer until the dough is smooth and bubbles appear.
Cover again and let it go for 20-30 minutes. Halve the yeast dough. Form each half of the dough into a roll of approx. 30 cm on a lightly floured baking board. Place on a lightly greased baking tray.
Cut the yeast dough rolls diagonally at a distance of 5 cm with a sharp kitchen knife approx. 1/2 cm deep. Let it rise again for about 30 minutes. Brush with salt water and bake in a preheated oven (electric: 200 °C/ gas: level 3) for approx. 30 minutes until golden brown.
Spread the white breads with salted water from time to time during the baking time. This gives them a nice brown crust. Remove the white breads from the oven and let them cool completely.