1. Mix both kinds of flour, 1 tbsp sugar, 2 tsp salt, dried yeast and sourdough extract in a bowl. Pour in 450-500 ml lukewarm water and knead everything by hand for approximately 7 minutes until a smooth dough is formed. Allow to rise, covered, in a warm place for approximately 45 minutes.
2. Peel and finely chop the onion. Heat oil in a pan. Saute the onion. Sprinkle with 1 level tablespoon sugar; turning, caramelize until golden brown. Remove, allow to cool briefly.
3. Chop walnuts coarsely. Knead onion, walnuts, and cranberries into the dough. Form a round loaf of bread. Roll the loaf in a small amount of rye flour. Douse a baking sheet with water. Lay down parchment paper and sprinkle with a small amount of water. Place the bread on top. Allow to rise, covered, for approximately 20 minutes.
4. Preheat oven (electric cooker: 250 °C/ circulating air: 225°C/gas: refer to manufacturer). Cut into bread using a sharp knife. Bake in hot oven for approximately 15 minutes. Then reduce oven temperature (electric cooker: 200 °C/ circulating air: 175°C/gas: refer to manufacturer) and bake for another 15-20 minutes. Allow bread to cool.