Clean the spinach, wash thoroughly and drain. Peel and finely chop the onion. Heat 1 tablespoon of oil in a saucepan. Fry the onion in it. Add the spinach and let it collapse.
Season with salt, pepper and nutmeg. Wash salmon, cut into 4 pieces, dab dry and sprinkle with lemon juice. Heat 2 tablespoons of oil in a pan. Fry the salmon for 5 minutes on both sides. Season with salt and pepper. Put yoghurt in a pot. Stir in cornflour. Bring the yoghurt to the boil briefly over medium heat, remove from the heat immediately. Season to taste with salt, pepper and sugar. Arrange spinach and salmon on plates.
Put yoghurt in a pot. Stir in cornflour. Bring the yoghurt to the boil briefly over medium heat, remove from the heat immediately. Season to taste with salt, pepper and sugar. Arrange spinach and salmon on plates. Garnish with lemon slices and julienne. Serve with boiled potatoes