• Mix the salt and lemon zest with a few grinds of black pepper and spread all over the salmon fillet. Set aside for 30 minutes. Rinse off the salt, pat dry and slice into 4 equal pieces.
• If using duck fat, melt it gently at a low temperature. In a pan that will fit the salmon snuggly, place the slices of lemon on the bottom, this stops the salmon coming into contact with direct heat on the bottom of the pan. Place the salmon on the lemon slices, cover with duck fat or olive oil. On a very low light heat to 42C and maintain that  temperature for up to 20 minutes. The salmon should be tender and flakey. Lift out the salmon and drain on kitchen paper to remove any excess oil or fat. If you plan on making this dish again, you can save the oil or fat to use again.
• Flake the salmon into a bowl and leave to cool. Fold in the mayonnaise, creme fraiché, shallot, dill, tarragon, chives, lemon zest and season to taste. Keep in an airtight container in the fridge until ready to serve.

Fine herb bavarois

• Have a bowl with ice water at the ready. Bring a small pan of salted water to the boil. Blanch the spinach and herbs for about 5 minutes until they are completely tender - when you rub the leaves between your fingers they should fall apart. Remove with a slotted spoon and immediately plunge into the iced water. Once cold, remove and squeeze out the excess water. Place all the greens in a blender with a splash of iced water and blend on high speed until completely smooth. Pass through a fine mesh sieve and store in an airtight container in the fridge for up to 24 hours.
• Soak the gelatine leaves in cold water for 10 minutes. In a stand mixer with the whisk attachment whip the cream to medium peaks. Set aside and keep cold. Using a hand whisk, whisk the egg yolks, the herb puree, lemon juice and salt in a separate bowl until fully incorporated.
• Heat the water in a small saucepan over a low heat, squeeze excess water from the gelatin and add to the warmed water off the heat. Add this to the herb and egg mixture and whisk briefly.
• Fold the whipped cream into the herb mixture a third at a time. Once fully incorporated, put into a container, cover the top with baking parchment to prevent a skin forming and leave to set in the fridge for 3 hours

To serve

• Divide the salmon between 4 soufflé style dishes or small kilner jars, top each with a quenelle of the fine herb bavarois. Garnish each jar with some dill fronds. Serve with slices of your favourite toasted bread and the extra bavarois on the side for everyone to enjoy.