Langoustine and mussel chowder with herb celery

Method

1. If using cooked langoustines, go to step 3. If using raw langoustines, put them into a saucepan large enough to hold them and all the mussels, then add 300ml water and ½ tsp salt. Cover, bring to the boil and steam for 3 minutes. Uncover the pan and turn the langoustines over once or twice. Add the mussels, cover the pan again and steam for a further 3-4 minutes until the mussels have all opened (discard any that don’t open).
2. Tip the langoustines and mussels into a colander set over a big bowl, to collect the cooking liquid. When they have cooled slightly, remove the langoustines and mussels from their shells (keeping 8 mussels in the shells) and set aside, reserving the langoustine shells.
3. If using cooked langoustines, remove from their shells and set meat and shells aside. Put the mussels into a medium pan with 300ml lightly salted boiling water. Cover and cook over a high heat for 3-4 minutes. Discard any mussels that don’t open, then drain, keeping the cooking juices (as in step 2). Shell the mussels, except for 8 of them. Set aside. Discard the shells.
4. Melt 25g of the butter in a large pan, add the langoustine shells and 2 of the bay leaves, then fry for 1 minute. Add the wine and the reserved cooking liquid. While it is bubbling away, crush the shells with the end of a rolling pin to release all their flavour into the liquid. Cook for 3-4 minutes, then pour back through the colander into the bowl.
5. Heat the rest of the butter in a pan, add the onion and bacon, then cook gently until the onion is soft but not coloured. Add the potato and cook for 1-2 minutes. Stir in the flour, then add the milk, cream and remaining bay leaves, and strain in the flavoured liquid using a fine sieve to remove any small pieces of shell. Simmer for 5-7 minutes until the potato is tender.
6. Stir in the langoustines and shelled mussels, then taste and adjust the seasoning. Ladle into warmed soup plates. Garnish with a mussel in the shell and the herb celery. Sprinkle with the crumbled water biscuits, if you like, then serve.