Add all-purpose flour, crushed caraway seeds, salt, shredded boiled potato (or mashed potato puree), and lukewarm water to the fermented starter.
Stir with a wooden spoon, then turn the mass onto a floured work surface. Knead the dough well by hand. The dough is quite sticky, so expect to end up with some dough on your hands.
Return the dough to the bowl and let it rise for another 45–60 minutes. I put the dough back in the oven to proof.
Prepare a round bowl and a clean tea towel. Dust the cloth evenly with flour and line the bowl with it. Carefully transfer the raised dough to a bowl lined with a floured tea towel. Cover the bowl with a clean tea towel or plastic wrap and let it rise for another 30-45 minutes.
About half an hour before the bread is proofed, turn the oven to 450°F (230°C). Place the Dutch oven, including the lid, in the preheated oven and let it heat up.
Prepare a cooling rack and heat-resistant oven gloves on the table next to the oven. Open the oven and, if it has telescopic rails, slide them and the pre-heated dish out. With gloves on, carefully remove the lid and place it on the cooling rack.
Put the raised bread into the pot. Cover it with the lid, slide the rails back in, and close the oven door. Bake covered for 30 minutes, then remove the lid, reduce the temperature to 375°F (190°C), and bake for another 10 minutes or until a crusty skin forms.
Turn out the bread and place it on a cooling rack. Leave to cool for at least two hours before slicing with a knife.