Preheat the oven to 120˚C.
Place the Parma ham slices on a baking tray and transfer in the oven. Bake for 10-12 minutes or until the Parma ham has crisped up. Remove from the oven and set aside to cool.
To continue, in a saucepan, drizzle some oil and add the leek. Season with salt and pepper and cook over low heat for 4-5 minutes until the leeks are just softened. add a drop of white wine if desired and a touch of fresh butter last minutes to add extra flavours.
Next, warm up the mash potato and keep aside.
Then, in a large non-stick pan, over medium heat, drizzle a little of oil and add the halibut. Season with salt and pepper and cook on one side for 3-4 minutes until the sides are starting to colour.
Flip the fish pieces and turn down the heat to low adding the butter. spoon the foaming butter over the fish pieces and continue to cook for a further 2-3 minutes until the fish is cooked through. The render of heat will continue to cook the fish but to be safer cook the fish fully. Remove the fish from the heat.
Spoon the wild garlic pesto on each serving dishes. Add the mash potato in the centre and spoon the leeks. Top with the halibut and crisp of Parma ham.
Enjoy immediately while piping hot.