Reserve the fennel greens and inner skins for the garnish.
Lightly sauté the fennel slices in olive oil before serving.
Lightly sauté the fennel pieces, celery and shallots in olive oil, add the fish carcasses and garlic, deglaze with white wine and cognac, fill with water, season with a tiny bit of salt. Once gently bring to a boil, then just steep at low temperature for an hour. Season with salt, pepper and a little bit of Pernod. Garnish: fennel slices, tomato concasser, fennel greens, crayfish, loup de mer, mussels, turbot…