For the sauce mash the tomatoes. Peel the onions. Dice one onion. Cut remaining onions into fine rings. Peel garlic and chop finely.
Heat oil in a pot, fry onion cubes and garlic, sprinkle with sugar and fry briefly while turning. Stir in mustard and marjoram. Deglaze with pureed tomatoes and bring to the boil. Season to taste with salt, pepper, paprika, Worchester sauce and Tabasco. Put the sauce aside. Wash the meat and pat dry. Season with salt and pepper. Place the meat, bacon and half of the onion rings on edge in a roasting pan, close together. Pour approx. half of the sauce over the meat and sprinkle the remaining onion rings on top.
Season with salt and pepper. Place the meat, bacon and half of the onion rings on edge in a roasting pan, close together. Pour approx. half of the sauce over the meat and sprinkle the remaining onion rings on top. Cook in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 1 1/2 hours. Serve garnished with oregano. Rest of sauce extra rich