Knead the flour and butter and chill. Peel onion and garlic and chop finely. Clean and wash the spinach. Wash and chop parsley.
Wash the fish fillets, dab dry and halve lengthwise. Season with pepper, cover each with 1 slice of salmon and sprinkle with some parsley. Roll up the fillets and fix them with skewers.
Heat 1 tablespoon of oil in a saucepan. Sauté half the onion in it. Add wine, 1/4 l water and broth, bring to the boil. Cover the plaice rolls and let them simmer at low heat for about 10 minutes.
Heat 1 tablespoon of oil in a large pot. Fry the rest of the onion and garlic. Add the spinach and cover and let it collapse.
Remove the rolls from the stock and keep warm. Bring the stock to the boil and simmer a little. Stir in the flour butter bit by bit with a whisk and simmer for about 5 minutes. Season with salt, pepper, 1 pinch of sugar and Noilly Prat.
Mix any remaining parsley with the spinach. Season spinach with salt, pepper and nutmeg. Serve everything. A wild rice mixture tastes good with it. Drink tip: cool white wine, e.g. Riesling.