600 g mussels
2 1/2 chopped onions
250 ml dry white wine
12 parsley sprigs + 1/2 cup chopped parsley
2 tbsp butter
2 cups finely chopped leeks
2 cups diced fennel
clam juice (optional)
fresh thyme sprigs
2 bay leaves
300-400 mg halibut fillets
scallops
250 ml crème fraîche
2 large egg yolks
Put washed mussels, 1/2 of onion, wine, 8 parsley sprigs in a large pot, cover and cook for approximately 5 minutes. Transfer mussels. Strain cooking liquid, discard onion and sprigs. Make 2 cups of this liquid.
Sauté the rest of onions, leeks and fennel for about 7 minutes in butter. Add mussel liquid, 4 parsley sprigs, clam juice, thyme, bay leaves. Simmer for about 25 minutes. Add scallops and halibut and cook for another 4 minutes. Transfer fish and scallops. Discard parsley, thyme, bay leaves.
Whisk crème fraîche and egg yolks, also whisk in 1/2 cup of hot liquid. Gradually stir yolk mixture and cook for 5 minutes. Return fish, scallops, mussels and heat everything for 5 minutes. Stir in chopped parsley and serve.