For the walnut bread, first prepare the sourdough. To do this, mix the barley with water and let it rise for 24 hours, covered with a damp cloth.
Then add rye flour and water, mix and leave covered with a damp cloth for another 10 to 12 hours. Do not forget to take away a gerstel (about 100 g) for the next bread.
For the main dough, dissolve yeast in water, mix with remaining sourdough and flours. After 1 to 2 minutes add salt and towards the end of the mixing time add walnuts. Knead everything until a smooth dough is formed. Cover with a damp cloth and let rest for 40 to 50 minutes.
Then divide in half, shape into two loaves and place in round simperl (proofing baskets). Cover with a damp cloth and let ferment for another 50 to 60 minutes. Turn the loaves out onto a prepared baking sheet, cut once lengthwise, and place in an oven preheated to 240°C. Pour a cup of water on the bottom of the oven and bake at falling heat (180 ºC) for 40 to 45 minutes.
Let the finished walnut bread cool and enjoy.Gerstel:In order not to need a few days each time to make sourdough, there is a method to preserve the finished sourdough for a few weeks. To do this, take about 50 grams of the finished sourdough, mix it with some rye flour (about 150 to 200 grams) and rub this mixture through your hands until you get a dry, crumbly mass. This is then called a “Gerstel”.