Fry the Maultaschen in clarified butter until crispy. Roughly dice the onions and fry them briefly. Add the sauerkraut, add about 2 cups of water and add the vegetable stock. Mix in the can of tomatoes, then mix in frozen herbs, caraway seeds and other spices. Bring everything to the boil while stirring and then simmer over medium heat for about 20 minutes.
When most of the liquid has evaporated, stir in the sour cream and season with salt and pepper.