Soak rye meal in 1⁄4 l water for about 12 hours.
Crumble the yeast and dissolve in 600 ml of lukewarm water. In a large bowl with soaked grist, flour, sourdough, beet syrup, 3 1⁄2 Knead tsp. salt and sugar to a smooth dough. Finally knead in the nuts. Cover the dough and let it rise in a warm place for about 1 hour until it has doubled in volume.
Grease two box moulds (30 cm long, approx. 2.5 l capacity and 25 cm long, approx. 1.5 l capacity). Approx. 2⁄3 Put dough into the large form, the rest into the small form. Cover and leave to rise again for approx. 30 minutes.
Brush the breads with water. Bake in the preheated oven (electric cooker: 225 °C/circulating air: 200 °C/gas: see manufacturer) for approx. 10 minutes. Switch the temperature down to 200 °C (circulating air: 175 °C/gas: see manufacturer). Bake the small bread for another 35-40 minutes, the large bread for 45-50 minutes. Let it cool down.