Finely chop celery, onion and fennel and garlic. Keep 1 piece of fennel aside as garnish. Stew in large pot, let it stew well and extinguish with white wine. Add broth and let it boil until the vegetables are cooked. Once they are done, add the mussels and let it cook for 3-4 minutes until the mussels are open.
Finely chop the sidewalk fennel and mix the mustard under the whipped cream, season with salt and pepper.
Put a large sieve on another large pot and carefully pour in the cooking liquid, mussels and vegetables. This way you catch the cooking liquid in the big pot and you can remove the mussels from the shell.
Once the mussels are out of the shells, these go together with the vegetables at the cooking liquid to mix together so make sure that no shells are included.
Mix well until everything is fine and smooth mixed. Season with and sieve.
Serve the soup in the glasses or bags and finish with mustard dream, finely chopped fennel, parsley and saffron wire.