Combine the mince with 1/2 cup water and 3 tbsp oil. Put it on the stove to braise. Once the water evaporates and the mince turns to bits, add the washed rice, savory, black pepper and cumin to taste. Stir several times and remove from the stove. Carefully tear the sauerkraut leaves from the sauerkraut head.
Put mince and rice filling on top of each sauerkraut leaf and wrap it up. Arrange the prepared sarma in a large glass cook pot with a lid. Pour water over them so that they're covered, add bay leaf and put in the oven to bake, with the lid on. Turn the oven up to 392°F (200 °C) and bake until ready - the rice in the sarma needs to fully cook and most of the liquid in the container needs to evaporate.
To make the sauce, put the grated onions + black pepper to taste in the oil and butter. Stir several times, be careful not to have the onions redden. Sprinkle on the flour. Braise until golden, take the container off the stove. To the braised flour, pour in the sauerkraut juice, mixed with the water and yoghurt, while stirring nonstop.
Put it on the stove once again and boil the sauce while stirring to the desired consistency. Taste it to see if it needs more salt and add some if needed. Serve the sarma, with the sauce poured over them and decorated with fresh parsley if desired.