For the sourdough, mix the sourdough with the water and rye flour without lumps and cover with a damp cloth or lid and let rise for 15-20 hours at a good room temperature.
Then take away about 100 g for the next bread baking!
Pour just enough boiling milk over the walnuts to cover the nuts and let them cool down.
For the main dough, dissolve the yeast in the water, mix with the remaining sourdough and the types of flour. After 1 to 2 minutes add salt and towards the end of the mixing time add walnuts (WITHOUT MILK).
Knead everything until you get a smooth dough. Cover with a damp cloth and leave to rest for 40 minutes or until it has risen twice.
Then halve, shape into two loaves and place in round Simperl (proofing baskets).
Cover with a damp cloth and let ferment for another 30 to 40 minutes.
Turn the bread out onto a prepared baking sheet, cut once lengthways and put in the oven preheated to 250 ° C.
Pour a cup of water on the bottom of the oven and bake for another 40 to 45 minutes after about 10 - 12 minutes (190 ºC) on the lower heat.