Moules de bouchot de la baie du Mont Saint-Michel au cidre (French mussels Mont Saint-Michel way)

For ➍
2 kg moules de bouchot*
6 dl Normandy cider (or white wine)
3 red onions, finely chopped (or shallots)
3 cups finely chopped parsley
60 g flour
60 g unsalted butter
3 dl cream
pepper

Clean the mussels. Remove the threads between the mussels, then wash in 2 baths of cold salted water. Keep them cold.
Pour ½ of the cider into the pot, add the mussels and pepper, then cook over high heat. When the mussels are open, remove them from the pot and strain the mussel juice.
Reserve the juice and keep the mussels warm. Place the butter in a pan, then add the chopped onions, cook until they become golden. Add flour, stirring with a wooden spoon to avoid lumps, then gradually pour in the cooking juices, cider and reduce to ⅓.
Stir in the cream, stirring, parsley, make a broth and remove from heat.

Serve and top the mussels with the cream sauce.

*The 'moules de bouchot' are cultivated on wooden stakes planted in the sea to avoid predators. It produces small, delicious mussels. A shipwrecked Irish or Scott seems to have invented the poles to hunt birds in the 13th century, but when mollusks attached themselves to the wood, it became a better trade. It was widely spread along the French Atlantic coast, and was regulated in the late 17th century. After WWII, the production was reactivated in Vivier-sur-mer, and has become a main succes in Normandy, followed by new mussel fields on the Atlantic shores.