Scrape and clean the mussels thoroughly, then put them in a wide, deep pan with the wine, shallots and parsley.
Cook over medium heat until the mussels have opened.
Drain the mussels when they have cooled down a little, but reserve the liquid.
Shell them and chop them finely.
Chop the onion and celery finely and cook them gently in 30 g (1 oz.) butter until translucent.
Strain the mussel liquid, add 2 tb of it to the vegetables, and simmer until all the liquid has evaporated.
In another pan, make a roux with 30 g (1 oz.) of butter and 1 tb of flour, add 1 dl (3,3 fl. oz.) of the mussel liquid and 2 dl (6,6 fl. oz.) warm milk, and cook, stirring with a wooden spoon, until the sauce is smooth and thick.
Add the chopped mussels, onion and celery to the sauce and beat in gradually 3 egg yolks and the lemon juice.
Check the seasoning, bring gently to the boil, then turn off the heat and let the mixture cool a little.
Pour the mixture onto a cold slab or a very large plate, allow to go thoroughly cold, then cut the paste into egg-sized pieces.
Beat the egg whites until very stiff.
Roll each egg-sized bit of paste in your hands and shape into oval patties.
Roll these in flour, dip them into the egg whites, roll in breadcrumbs, and fry in oil until golden and crisp.