(I found the recipe in German here.)
400 g sourdough (rye) (If you don’t know it, take a look here.)
375 g rye flour
375 g whole wheat flour
400 ml water
2 teaspoons salt
1 heaped teaspoon bread seasoning
1 teaspoon sugar
optional: a bit of yeast (If your sourdough isn’t so strong.)
Mix all of it together thoroughly – Add the water at last, but don’t put all of it in at once.
Let the dough sit for half an hour – Then shape a loaf of bread an put it in a pot or bowl laid-out with a floured dishtowel (or a dough basket) to let it rise for 2 hours.
After waiting 2 hours or more, preheat your oven to 240° C (460° F). Put the dough loaf on a baking sheet lined with parchment paper and bake it for 10 minutes. Spray water on it in between to get a nice crust.
After those 10 minutes, reduce the temperature to 200° C (390° F) and bake for another 45-50 minutes.
Look if it’s nicely browned everywhere, and when it is, try if it’s done by knocking on the bottom side – If you get a hollow sound, your bread is ready to come out of the oven.
Slice it up and bring it to people you love.