Soak the buns. Clean the cabbage, cut out the stalk. Put cabbage in boiling salted water and remove 12 leaves bit by bit. Use the rest of the cabbage for other purposes. Peel and finely chop the onion.
Knead minced meat, onion, egg and squeezed out roll. Season with salt, pepper, marjoram and mustard. Cut the middle rib of each cabbage leaf flatter. Place 2 cabbage leaves on top of each other. Divide the minced meat into 6 parts, put them on the cabbage leaves and fold them into packages.
Wrap with kitchen string. Cut bacon into strips. Heat oil in a frying pan. Fry the bacon in it and take it out. Fry cabbage parcels in bacon fat on both sides. Add bacon. Deglaze with broth, bring to the boil.
Cook in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 45 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 pepper. 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.