Terrine of Seafood with Pastis Fumet

To make the fumet

Heat the olive oil in a saucepan, add the mirepoix, fennel and leek and soften in the oil over a low heat for 5 minutes. Add the rest of the ingredients and bring to the boil, simmer for 20 minutes and then pass through a fine sieve into a wide pan. Bring to the boil and simmer. Poach each fish in the fumet individually until it is just co