Heat the oil and fry the minced meat in it until crumbly. Add the leek cut into rings and fry them briefly, then season with cumin and deglaze with the water and gravy. Stir in the sour cream and simmer for 5 minutes.
Meanwhile, cut the dumplings into cubes and place in the baking dish. Season the minced meat sauce with salt and pepper and spread over the dumpling pieces. Sprinkle with the grated cheese and bake at 220 ° C until golden brown (10-15 minutes).