Le Gruyère AOP-crusted halibut with leek fondue and parsley sauce

First give the halibut a quick cure, as this will help the fish firm up and not flake apart whilst cooking. Mix the salt and sugar together and then use the mixture to cover the halibut portions completely. Leave to cure for 30 minutes in the fridge, then rinse under a tap and pat dry

Mix the breadcrumbs, cheese and herbs together, then slowly drizzle in the melted butter. Tip out onto a sheet of greaseproof paper, bring together into a ball, then place another sheet of greaseproof paper on top and use a rolling pin to roll the ball into a 2mm-thick sheet

Place the sheet into the fridge for 30 minutes to firm up a bit. Once set, cut into portions the same shape as your halibut fillets and gently transfer the crust to sit on top of each fillet

Slice the leeks very finely, then blanch in salted boiling water for 8 minutes

Refresh in iced water then drain, squeezing out as much water as possible. Melt the butter in a large frying pan and add the leeks. Season with plenty of salt and pepper, then cook gently, keeping warm until ready to serve

To make the sauce, bring the fish stock to the boil with the butter. Transfer to a blender and add the parsley leaves. Blend on full speed for 5 minutes then pass through a fine sieve. Taste and season, then keep warm or reheat before serving

To cook the fish, preheat an oven to 50°C. Place the fish in the oven for 8 minutes – this will just warm up the fish and cook it very lightly. Preheat a grill to high at the same time, then after the 8 minutes is up, transfer the halibut fillets to the grill to melt and then crisp up the crust – it should be a deep golden brown

Spoon the sauce in the centre of each plate and top with leeks and then the crusted fish