For the sourdough, mix the rye flour with the water and the topping well the day before and cover and let ripen for 24 hours at room temperature.
The next day, remove 50 g from the sourdough and place in the refrigerator for the next bread.
Put the rest of the sourdough in a large mixing bowl. Mix in the flour and the remaining ingredients. Knead everything with the mixer for about 5 minutes. Cover the dough and let rise for 30 minutes.
Then place the dough on a floured baking surface, work with floured hands, shape into a loaf and place in a floured proving basket. Cover and leave the loaf to rise to about twice its size.
Preheat the oven to 250 ° C top / bottom heat. Push in the drip pan at the very bottom.
Turn the dough out onto a baking sheet lined with parchment paper.
Put the bread in the oven and bake for 15 minutes, pouring a glass of water onto the hot drip pan at the beginning (steaming). Brush the bread with water, turn the oven down to 200 ° and bake the bread for another 45 minutes.
Take the bread out of the oven and tap on the bottom of the bread. If it sounds hollow, the bread is finished baked.