For the wholemeal bread, dissolve sourdough in a little water, stir into about 100 g of preheated flour and let stand overnight. If necessary, soak flaxseed overnight in 500 ml of water.
The next day, add flour, salt, sourdough, dissolved yeast and possibly flaxseed to the bowl. Add lukewarm water, knead well to form a dough and let rise for about 40 minutes.
When the dough has doubled in volume, place it in a greased loaf pan (or form it into a loaf) and let it stand for another 5 minutes. Bake in the preheated oven for about 90 minutes at 180-200 °C with bottom heat.