Preheat oven to 200C. Set sous vide machine to 40C.
For the Vegetable stock, heat butter in a large pot over medium heat then add all vegetables. Add enough water to cover vegetables completely then reduce heat to low and simmer for 30 minutes. Remove from heat and strain through a sieve lined with muslin cloth into a clean bowl. Set aside until needed.
For the Braised Onions, place onions into a small saucepan and cover with Vegetable Stock, ensuring the onions are fully submerged. Simmer over low heat until tender, about 20 minutes.
Heat a medium frypan over medium heat and add butter and oil. Remove onions from vegetable stock and place, cut side down, onto the pan. Cook until cut side is caramelised, about 5-7 minutes. Remove from the pan and separate the layers of onion and lay out onto a tray. Set aside until needed.
For the Sauce, heat a medium frypan over medium heat. Add oil and wings and fry until browned. Cover with Vegetable Stock and add the sprig of dill then cook until reduced by half, about 15-20 minutes. Remove from heat, season to taste and set aside until needed.
For the Pumpkin Purée, line a baking tray with baking paper. Spread diced pumpkin onto the tray and drizzle with oil and a sprinkle of salt. Place into the oven and roast until just golden and tender, about 25-30 minutes. Remove from oven and transfer to a canister with half of the butter and half of the cream. Purée with a stick blender until smooth, adding remaining butter and cream until purée is completely smooth. Add some of the vegetable stock to the purée to loosen if required.
For the Confit Salmon, first carefully remove skin from fillets and reserve.
Make a brine solution by combining 100g salt flakes and 1 litre of cold water in a medium sized bowl. Add salmon fillets and set aside to brine for 30 minutes.
Remove salmon fillets from brine and rinse under cold water. Pat dry with paper towel then carefully place into a sous vide bag. Add rice bran oil, bay leaf, dill and lemon zest then seal. Place sous vide bag into the preheated sous vide machine for 25 minutes. Remove from water bath and set aside until required.
Meanwhile, for the Crispy Salmon Skin, line a baking tray with baking paper. Clean the pieces of skin to remove any remaining flesh and spread flat onto the pre-lined baking tray. Drizzle with oil and a sprinkle of salt flakes. Top with a second sheet of baking paper and a second baking tray on top to weigh down. Bake in the oven until golden and crisp, about 18-20 minutes. Remove from oven and set aside on the bench until required.
For the Foam, combine lemon juice, caper vinegar and soy lecithin in a small saucepan and set aside until required for serving.
For the Oyster Mushrooms, place butter into a medium frypan over medium heat and melt. Add mushrooms, gill side down, until caramelised then turn over and fry for a further minute. Remove from heat and set aside in the pan until required.
To finish the Foam, use a stick blender to blitz the reserved canister of mixture until a foam has formed on the top.
To serve, gently take the reserved inner layers of Braised Onion and place a few onto one side of each plate, grilled side facing upward. Spoon some mounds of Pumpkin Purée around the onions. Add a few of the Oyster Mushrooms and some nasturtium leaves. Use a teaspoon to spoon some of the Sauce into each onion layer. Remove Confit Salmon from the sous vide bag and carefully place onto the plate opposite the other side of the plate. Skim some foam from the top of the Foam canister and spoon over the salmon and vegetables and finish by resting a piece of the Crispy Salmon Skin resting on the salmon.