Peel onions and finely dice 3 onions. Drain the peppers and also cut them into fine cubes. Heat 1 teaspoon of oil in a pan. Fry the onions in it. Add paprika and steam for about 2 minutes.
Stir in tomato paste. Season to taste with salt and cayenne pepper. Leave to cool. Put sauerkraut, apple juice, 1/8 litre water, bay leaf and caraway into a pot. Bring to the boil, stir in 1 teaspoon of broth and braise covered for about 30 minutes.
Wash the rosemary and dab dry. Place the slice of meat on a work surface and sprinkle with salt. Spread the pepper and onion filling on top and roll up. Tie the meat roll with kitchen twine, tying the rosemary twigs tightly into it.
Quarter the remaining onion. Heat 3 teaspoons of oil in a frying pan. Fry the rolled roast in it while turning it all around. Add the onion and fry briefly. Season meat with salt and cayenne pepper.
Pour on 3/8 litres of water. Bring to the boil, stir in 2 teaspoons of stock. Roast in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 45 minutes, scoop the stock several times.
Remove the roast and keep it warm. Stir the starch with a little water until smooth. Thicken the stew with it. Season sauce with salt and pepper. Season sauerkraut with salt and pepper. Arrange everything.
Boiled potatoes taste good with it.