Knead the sourdough (there are recipes in the database), wheat flour, rye flour, salt and water for about 10 minutes with the food processor and let the dough rest for 30 minutes.
Then knead the dough vigorously by hand and divide it in half. Grind the dough pieces and let rise in the floured proofing basket or on the baking sheet for about 2 hours.
Preheat the oven well to 250 °.
Cut into the surface of the bread several times and bake for 10 minutes, steaming well.
After 10 minutes, reduce the heat to 200 ° and bake the bread for another 50 minutes.