Warm the buttermilk slightly and dissolve the yeast in it. Put all other ingredients in the bowl of a food processor and add the yeast-buttermilk mixture.
Knead everything for about 5 minutes on the highest speed with the food processor and line a microwave dish (glass with lid) with baking paper.
Preheat the oven to 200 °C and knead the dough again well by hand.
Form the dough into a loaf and place it in the bowl. With a lukewarm damp hand, smooth the surface of the loaf.
Score crosswise with a sharp knife, put the lid on and bake for about 70 minutes. Do not remove the lid before the end of the baking time and let the bread cool well.