Soak the buns. Clean the cabbage, cut out the stalk. Put cabbage in boiling salted water and remove 8 leaves bit by bit. Use the rest of the cabbage for other purposes. Peel and finely dice 1 onion.
Knead minced meat, onion, egg and squeezed out roll. Season with salt, pepper and mustard. Cut the middle rib of each cabbage leaf flatter. Put 2 cabbage leaves on top of each other. Divide the minced meat into 4 parts, put them on the cabbage leaves and fold them into packages.
Wrap with kitchen string. Cut onion into strips. Heat oil in a frying pan. Braise the onion strips for about 4 minutes and take them out. Fry cabbage parcels in onion fat from both sides.
Add the onion. Deglaze with stock, bring to the boil. Cook in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 30 minutes. If necessary, gradually add 1/4 litre of water. Peel and wash the potatoes and cook in boiling salted water for about 20 minutes.
Remove the cabbage rolls and keep warm. Stir flour with a little water until smooth and thicken the sauce with it, bring to the boil again and simmer for about 5 minutes. Season with salt and caraway. Add the cabbage rolls to the sauce.
Wash parsley, shake dry and chop. Drain the potatoes and sprinkle parsley over them. Serve cabbage rolls and parsley potatoes together.