Place a pan over medium heat. Add oil, diced onion, pancetta, parsley, and minced garlic. Cook for 5 minutes while stirring occasionally. Add the rice and cook for 1 - 2 minutes, then season with thyme. Pour in the beef stock. Cook until the liquid evaporates for about 5 minutes, then remove it from the heat and bring it to room temperature.
Add the ground meat to a large bowl. Add an egg and one teaspoon of salt and season with marjoram and ground black pepper. Add the rice mixture and stir to combine.
Clean the cabbage head and rinse under running water. Separate the cabbage leaves. With a knife, remove the tough ribs without damaging the cabbage leaves. Set the ribs aside. Cut the large leaves in half. Add a generous tablespoon of meat filling to the bottom of each cabbage leaf. Fold the bottom of the cabbage leaf over the meat. Fold the sides to the center and roll away from yourself as if you were making enchiladas. Repeat until you use all the ingredients. Grate the rest of the sauerkraut and finely chop the remaining ribs. Add half of the cabbage to the bottom of a large deep (oven-safe) pot. Add half of the cabbage rolls in a single layer, seam-side down. Leave a bit of space between the rolls. Spread the rest of the cabbage ribs and half of the sauerkraut over the sarma. Add the slab of bacon and arrange the rest of the sarma on top.
Place a rack on the bottom of the oven and preheat it to 180 °C / 350 °F. Place a pan over medium heat. Add oil and the flour and cook for 1 - 2 minutes for the flour to cook. Reduce the heat and add paprika powder and tomato paste. Cook for another minute. Remove from the heat. Add 200ml (3/4 cup) of beef stock. Whisk to get a smooth mixture, then add the rest of the beef stock. Pour the boiling mixture over the cabbage rolls in the pot. Add 250ml (1 cup) of water. Gently dip the rolls in the liquid and cover the pot with a lid.
bake the cabbage rolls (sarma)
Place a large pot with the stuffed cabbage rolls in the oven. Bake for 1 hour at 180 °C / 350 °F, then lower the heat to 160 °C / 320 °F and cook for another 3 hours. Serve with mashed potatoes or boiled potatoes.