1. Finely chop the shallots.
2. Scrub and clean the mussels thoroughly.
Place them in a pot with 1 knob of butter, the chopped shallots, and the white wine.
3. Cook the mussels covered over high heat for a few minutes until they open. Stir 2 or 3 times during cooking.
4. As soon as they open, remove the mussels from the pot while keeping the cooking juices. Place them in a shallow dish and keep them warm.
5. Put the cooking juices back on the heat. Mix 1 teaspoon of flour with the same amount of butter or margarine using a fork. Incorporate this mixture into the cooking juices of the mussels on the heat. Let it boil for a moment. Season with salt and pepper.
6. Pour the sauce over the mussels. Sprinkle with chopped parsley and serve.