Wash potatoes thoroughly and cook in boiling salted water for 15-20 minutes. In the meantime, stir curd, sour cream and lemon juice with a whisk until smooth. Season with salt and pepper. Put the quark dip in a cool place.
Drain the potatoes and let them evaporate for about 5 minutes. Then place the potatoes at intervals on a baking tray and press them flat a little with a potato masher. Melt the butter. Grate the parmesan finely. Brush each potato with a little butter and sprinkle with parmesan. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for about 15 minutes.
Clean, wash and cut the spring onions into rings. Cut the cress from the bed. Pluck salmon roughly. Spread curd dip into a deep form. Add parmesan potatoes and salmon. Sprinkle with spring onion rings and cress. Season with pepper. Arrange baked potatoes and serve.