Use a knife to remove the central bone from the salmon steaks. Remove any pin bones. Trim off the grey flesh on the belly of the fish but don't cut through the skin. Fold the skin back around the salmon steak to make the tournedos.
Wash and roughly chop the chervil. Crush the walnuts. Cut the smoked duck breast into very small cubes. Place the pine nuts in a hot frying pan and cook until lightly browned.
Peel the celeriac and cut into 1cm cubes. Peel the apple, remove the core and cut into small dice.
Place the celeriac in a hot frying pan, add the butter and then add enough water to cover the celeriac. Simmer until all the liquid has evaporated. Check the seasoning then add the apple and half of the chopped chervil. Set aside in a warm place.
For the vinaigrette: place the smoked duck, pine nuts, balsamic vinegar, olive oil and the rest of the chopped chervil in a bowl and mix. Season with salt and pepper.
Preheat the oven to 160°C.
Heat a non-stick frying pan to hot and add a dash of olive oil. Sear the salmon tournedos for 30seconds on each side then season with salt and pepper. Transfer the tournedos to a silicone baking sheet and finish cooking in the oven for 3 to 4 minutes.
To serve, use stainless steel serving rings to plate the braised celeriac. Place the salmon tournedos on top of the celeriac and drizzle the vinaigrette over the dish. Serve immediately.
«If you cannot find smoked duck, replace with lardons. Pan fry until crispy before adding to the dressing.»