Prepare sourdough with the wholemeal rye flour*.
Grate the cooked potatoes, squeeze or press through a potato ricer. Cool the mixture before further processing.
Melt the yeast in a little water and mix briefly with the rye and sourdough, salt, wheat flour and caraway seeds. This gives a crumbly mixture.
Then knead in the potatoes. Adjust the desired dough consistency by carefully adding lukewarm milk. The dough should not become too soft, otherwise the loaf will be too flat when baked.
Wipe the bread with a wet cloth and bake for ten minutes in the oven heated to the highest setting (275 degrees, top and bottom heat, no convection). Then reduce the heat to 225 degrees and bake for another 40 minutes.