Preheat the barbecue.
To make the pickled cucumber, place a small saucepan over a medium heat. Add the sugar and vinegar and heat until the sugar has dissolved. Remove from the pan and add the cucumber. Set aside.
Mix together the lemon butter ingredients in a small bowl.
Lightly oil the turbot on both sides, season and place white skin-side down on the barbecue. Cook for 4 minutes and turn over. Add a spoon of the lemon butter onto each tranche and cook for a further 5 minutes or until cooked through. Take off the barbecue and allow to rest. Remove the dark skin.
Place the leeks on the barbecue until charred. Spoon some of the lemon butter onto each leek and cook for a further 2 minutes.
Sauté the girolles in a saucepan with a splash of olive oil and a knob of lemon butter.
For the sauce, place a frying pan over a medium heat. Add the butter and cook until it turns a nut-brown colour. Add the lemon juice, fresh almonds and the remaining the ingredients. Season with salt and pepper.
To serve, place the turbot on a serving platter. Arrange the leeks and girolles around the edge and pour over the sauce.