Slice the shallot finely and dice the garlic. Sweat the shallot in a saucepan with the butter until the shallot is completely soft. Add the garlic and the thyme and cook for a further minute. Add the white wine to the pan and reduce this by half. Add the double cream and bring to the boil. Season with fine salt and keep to one side.
Prepare the mussels by removing the beards and then cook them in a pan with a tight fitting lid until all of the mussels are open.
Keep 3 mussels per plate in their shells and pick the rest to add to the sauce.
Finely chop the chives.
Preheat the oven to 200'C.
Heat a frying pan over a high heat until the pan is very hot. Season the halibut steak with salt.
Add a splash sunflower oil and fry the halibut flesh side down until it is golden brown.
Transfer to the oven for 5 to 7 minutes until cooked through. Remove the skin and serve flesh side up.
Wash the samphire in plenty of cold water and remove any damaged pieces and the tough stalks.
Prepare the girolles by washing and allowing them to dry on a cloth before cooking.
Whilst the fish is in the oven cook the samphire and mushrooms.
Cook the samphire for 3 minutes in rapidly boiling water and then drain. Mix in a knob of butter and season with some black pepper.
For the mushrooms: Heat a frying pan over a low heat
Add a splash of olive oil and cook the mushrooms until they are soft.
Season with salt and pepper.
Reheat the velouté on a low heat and add the mussels and shrimps until they are heated through. Add the chives at the last minute. Check the seasoning and add a squeeze of lemon juice.
Serve the halibut on a bed of samphire. Dress the plate with the velouté and finish the dish with the girolles.
«The halibut in this dish can be replaced with any white fish - brill, turbot, plaice.»