Prepare the lime jus: In a heavy-based saucepan melt 20g butter, add the shallots and sweat for 5 minutes without colour. Add the tomato and garlic and cook for a further 3 minutes. Sprinkle over the sugar and stir until dissolved. Add the sherry vinegar and reduce until the vinegar and sugar have caramelised. Add the Port and Noilly Prat and reduce by three quarters. Pour in both stocks and bring to the boil. Add the parsley stalk and reduce by a third. Pass the sauce through a fine chinois, return to the pan and reduce by half. Whisk in the remaining 40g butter and season to taste with salt, freshly ground pepper and lime juice. Once more, pass through a fine chinois.
Warm the crushed potatoes and add the sliced chives at the last minute to prevent them from discolouring. Lightly season the blanched baby leeks and trompette de mort mushrooms with salt and freshly ground pepper and place onto buttered paper. Have the lime segments at room temperature.
In a large heavy-based pan heat 30ml olive oil over a medium heat. Lightly season the John Dory with salt and freshly ground pepper and cook for 3 minutes until golden brown. Turn the fish over and cook for a further minute. Add the butter and allow it to melt before basting the fish with it. Once again, lightly season the fish with salt, freshly ground pepper and a squeeze of fresh lemon. Drain the fish on kitchen paper to absorb any excess oil and keep warm.
Heat the baby leeks and trompette mushrooms in a steamer for 2 minutes. In a cast-iron pan heat the remaining olive oil until almost smoking. Add the scallops and sear for 30 seconds on each side until golden brown, keeping them under-cooked in the centre. Remove from the pan and place on the kitchen paper with the John Dory. Lightly season the scallops with salt, freshly ground pepper and a squeeze of lemon.
Place an 8cm pastry ring in the centre of a plate and spoon the potato into it. Smooth the potato with the back of the spoon. Gently remove the pastry ring and lay the baby leeks across the potato. Place 2 scallops and 3 lime segments around the potato and leeks. Arrange 2 pieces of John Dory onto the leeks and spoon the lime jus over the fish and a little around the plate. Garnish with the julienne of trompette de morts mushrooms, sprigs of chervil and chive tips.