Rinse fillet cold and dab dry. Cut into thin strips. Clean, wash and chop the mushrooms. Peel onions and cut them into sticks. Fry meat in hot oil for about 5 minutes while turning.
Add mushrooms and onions and fry briefly. Dust with flour and pour on cream. Let it boil up once. Cut cucumbers into slices and add to the meat with the capers. Season with salt and pepper. Put them into an ovenproof dish. Grate cheese and sprinkle over it. Bake in a preheated oven (electric cooker: 200 °C/ gas: level 3) for about 10 minutes. Wash parsley, dab dry and chop.
Season with salt and pepper. Put them into an ovenproof dish. Grate cheese and sprinkle over it. Bake in a preheated oven (electric cooker: 200 °C/ gas: level 3) for about 10 minutes. Wash parsley, dab dry and chop. Sprinkle over the casserole