Prepare all the ingredients.
the onions.
them without browning in stewpan along with olive oil.
Add the pumpkin cut in large dice...
...and 2 dl water gradually.
Add salt and pepper.
Cook covered on low heat for about 20 minutes.
Meanwhile, scrape the mussel shells.
Place them in a stew pan...
...with white wine.
Cook covered for a few minutes...
...until they open. Drain them and keep their cooking juice.
Shell the mussels (keep a few shell on).
Once cooked, purée the pumpkin.
Add the juice of the mussels...
...the crème fraîche and pastis.
Dress and serve hot.