For the sauce, using a meat cleaver, chop the John Dory heads in half and the chicken drumsticks into three pieces.
Place a large, heavy-based pan over a high heat and leave for two minutes. Add the grapeseed oil, swiftly followed by the fish heads and drumsticks, and leave to colour for 1-2 minutes. When golden-brown, season lightly with salt, turn over and colour the other side.
Add the butter, stir and continue cooking until all the pieces are golden-brown – you will have to scrape away at the bottom of the pan to achieve this. Stir in the shallots, mushrooms, bay leaf and thyme.
Add vinegar and cook until it has completely evaporated. Add the Madeira and cook until all but a teaspoon has evaporated.
Add the stocks, bring to the boil and gently simmer for 30 minutes. Remove from the heat and set aside to rest for 10 minutes.
Drain through a colander and then pass the sauce though a fine sieve into a medium saucepan.
Return the sauce to the heat, bring to the boil and gently simmer until it has reduced enough to coat the back of a spoon. Check the seasoning and set aside to cool. (It should be a rich, sweet and sour mix of stock and fat in the approximate ratio of 2 to 1. Skim off any fat in excess of this.) Transfer to the fridge.
For the shallot purée, preheat the oven to 170C/325F/Gas 3.
Place a heavy-based casserole over a medium heat and leave for a minute. Add the butter, allow it to melt, then add the shallots and a generous pinch of salt. Cook for five minutes, stirring frequently.
Reduce the heat and continue to cook over a gentle heat for 15-20 minutes, still stirring frequently, until the shallots are completely soft and have a light-golden colour.
Add the cream, bring to the boil, then cover the casserole and transfer to the oven for ten minutes.
Remove from the oven, transfer to a food processor and blend to a smooth purée. Pass through a fine sieve into a bowl, check the seasoning and set aside to cool slightly before transferring to the fridge.
For the black rice, rinse the rice under cold running water. Place in a heavy-based saucepan, cover with the chicken stock, season with a pinch of salt and place over a medium heat. Bring to the boil and gently simmer for 20 minutes, or until tender.
Remove from the heat, leave to sit for five minutes, then drain, reserving 230ml/8fl oz of the cooking liquor. Set both the rice and the reserved cooking liquor aside to cool to room temperature.
Place the corn in a saucepan, cover with water, bring to the boil and simmer for about 15 minutes, or until tender.
Drain and refresh under cold running water for five minutes. Hold the corn upright on a board and use a sharp knife to cut the kernels away.
Place a heavy-based saucepan over a medium heat and leave for a minute. Add the butter, followed by the onion and a pinch of salt. Cook for five minutes, stirring frequently, until soft and translucent. Add the mushrooms and cook for a further 2-3 minutes. Add the corn kernels and mix thoroughly. Season to taste with salt and freshly ground black pepper. Set aside to cool.
For the langoustine claw beignet, coat the claw meat (or prawns) by first dipping them in the flour, then the egg and finally the breadcrumbs, ensuring you get one thin, even coating of crumbs. Cover and transfer to the fridge.
To serve, reheat the shallot purée and set aside.
Melt 20g/½oz of the butter in a pan, add the rice and the sweetcorn mix and heat through. Add the cooked langoustine claw meat (or crab meat) and the tarragon and fry for two minutes. Remove from the heat and keep warm.
Reheat the sauce and set aside.
For the John Dory, preheat the oven to 170C/325F/Gas 3.
Place two large, heavy-based, non-stick frying pans over a high heat and leave for a minute. Divide the grapeseed oil between the frying pans. Season the John Dory fillets with salt and freshly ground black pepper. Add the fillets to the frying pans skin side down and cook for 1-2 minutes, or until golden.
Divide the butter between the pans, turn the fish over and cook for 30 seconds. Transfer the fish to a roasting tray, tip the oil and butter over the top and place in the preheated oven for five minutes. Remove and set aside to rest for two minutes.
To serve, transfer one tablespoon of the juices from the roasting tray to the sauce and stir briefly.
Fill a deep-fat fryer (or deep saucepan) with vegetable oil and heat to 180C/350F.
Deep fry the langoustine claw beignets until golden-brown. Remove and drain on a dish lined with kitchen paper. Then squeeze the lemon wedges over them.
Reheat 230ml/8fl oz of the reserved black rice cooking liquor. Season with salt and freshly ground black pepper, add the lecithin and blend with a hand blender – it should froth up but will only do this if the liquid is hot but not boiling.
Place four small spoonfuls of shallot purée on each plate. In the centre of each plate, put a small heap of black rice mix and sit a fillet of John Dory on top. Spoon a generous tablespoon of sauce over the fish and surround it with the black rice froth. Garnish with a beignet and serve immediately.