Clean and wash the spinach. Blanch briefly in boiling salted water, remove and drain. Peel and wash the potatoes and cook in boiling salted water for about 20 minutes. In the meantime, remove the crusts from toast. Grind toast finely in a universal chopper. Cut smoked salmon into small cubes.
Melt butter and mix with toast and smoked salmon. Wash salmon fillets, dab dry and season with salt and pepper. Place in an ovenproof dish and spread the smoked salmon mixture on the fillets. Bake in a preheated oven (electric range: 225 °C/ gas: level 4) for approx. 15 minutes. In the meantime, stir egg yolk, mustard and honey until smooth. Stir in 50 ml oil bit by bit. Add yoghurt and season with salt, cayenne pepper and vinegar. Wash the dill, dab dry and pluck off except for something to garnish. Chop dill finely and stir into the sauce. Drain potatoes and let them evaporate. Peel onion and chop finely. Heat the remaining oil in a pan and sauté the onion.
Add yoghurt and season with salt, cayenne pepper and vinegar. Wash the dill, dab dry and pluck off except for something to garnish. Chop dill finely and stir into the sauce. Drain potatoes and let them evaporate. Peel onion and chop finely. Heat the remaining oil in a pan and sauté the onion. Add the well squeezed spinach, heat it and season with salt and nutmeg. Arrange salmon fillets with spinach, potatoes and sauce on plates and garnish with the remaining dill