Put the types of flour in a bowl and mix, make a well in the middle and pour in the sourdough. Add all ingredients and stir with the dough hook for approx. 8 minutes.
Let rest for 1/2 hour, then knead firmly, put in a proofing basket and cover again for approx. 1.5 hours.
Preheat the oven to 230 °, insert the bread, steam it firmly for the first 1/4 hour, then switch back to 200 ° and bake for 50 minutes.