Take a thick-bottomed pan and add the shallots, parsley, wine, fish stock and the cleaned mussels. Cover with a lid and cook over a high heat until the shells open. Drain off all the cooking liquor in a colander set over a clean bowl to retain the cooking juice. Carefully check the mussels and discard any that have not opened. Place in a dish and cover to keep warm.
Make a roux from the flour and butter: pour over the cooking liquor, ensuring it is free from sand and stirring continuously avoid lumps. Correct the seasoning and garnish with more chopped parsley. Pour over the mussels and serve.
Try something new; add little red chili and replace the parsley with the coriander.