First make the court bouillon. Heat the butter in a large pan and sauté the carrots, celery, leeks and onions for a few minutes. Add the bay leaf with the thyme and stir in the coriander and fennel seeds. Pour in the white wine and vinegar and cook down for few minutes. Cover with water and bring to the boil, then simmer for 30 minutes. Strain into a clean pan and leave to simmer gently until required.
For the turbot, season the turbot fillet with salt and freshly ground black pepper, then cut into four portions. Add to the court bouillon and cook for 3-4 minutes. Remove the fish using a slotted spoon and set aside. Court bouillon can be kept in the fridge/freezer for a later date if needed.
Open the oysters, retaining the juices. Place the oysters in a sieve set in a bowl and drain, reserving the juices. Heat the reserved oyster juices in a pan, add the oysters and poach for one minute. Add the soy sauce, butter and shallots, then stir in the chopped chives. Heat for a further 2-3 minutes. Drain the oysters before serving.
Meanwhile, make the seaweed salad. Whisk the olive oil and vinegar in a bowl and add the shallots to make a vinaigrette. Place the seaweed in a separate bowl and dress with the vinaigrette. Toss together to coat.
To serve, place the turbot on the warm plates, arrange the dressed seaweed alongside and place the oysters on top.