Roast turbot with hot citrus vinaigrette and diced confit of citrus-rinds

Servings: 4
Ingredients

1 turbot fillet, weighing 800 gr
1 pinch of finely ground cooking salt
15 ml mild extra-virgin olive oil
1 pinch of Maldon salt flakes

For the confit
5 citrus fruit: 1 lemon, 1 grapefruit, 1 orange, 1 mandarin, 1 lime
100 gr  sugar
100 ml water

For the vinaigrette (prepare at least 12 hours ahead)
60 ml  each of freshly squeezed grapefruit, lemon, orange, mandarin and lime juice (you will need more fruit than one fruit of each)
60 ml  passion fruit juice, sieved of seeds
600 ml  extra-virgin olive oil
2 heads of garlic, each clove skinned and thinly sliced
4 gr  powdered agar-agar 

Procedure

To prepare the vinaigrette, squeeze the juice of the skinned fruit to make up the quantity required and bring to a boil in a stainless-steel pan. Remove. In another large heavy-bottomed pan, heat the sliced garlic gently in the olive oil until just golden, remove the pan from the heat, cool until the oil is the same temperature as the juice and mix the two together. Cover in a cool place for at least 12 hours. Strain.

For the confit, slice off one end of each fruit to make a levelled base, set the fruit on this and shave off slices of zest and pith approximately 4-5mm (just under ¼ in) thick with a very sharp knife. Blanche each type of fruit skin separately, drain and refresh; repeat three times. Place the sugar and water together in a heavy-bottomed saucepan and bring to the boil. Cook the sliced rinds in the sugar syrup, each type in a separate pan for about a minute each, and leave to cool in the syrups. Remove the rinds and cut them into 4-mm (1/6-in) square dice.

Shortly before serving, soak the agar-agar in cold water for a few minutes until it becomes elastic. Remove and drain well. Heat 100 ml (4 fl oz) of vinaigrette in a saucepan, add the agar-agar gelatine and dissolve away from the heat. Mix back into the rest of the vinaigrette and heat gently.

Salt the turbot lightly on both sides. Heat the olive oil in a heavy pan and sauté the fish until golden. Place in the middle of a very cool, dry oven (at 10% humidity or with a little water in an oven dish on a lower rack), preheated to 110 °C/225°F/gas mark 4-5, and cook for 5-6 minutes. Meanwhile, warm four deep plates. Spoon four tablespoons of the vinaigrette onto each plate. Divide the fish into four fillets and place one on each plate, putting two dice of each type of rind around the fish. Season with a little Maldon salt.