Trim the salmon fillets, season with salt and pepper.
Place in a dish and add the lemon juice, wine and enough water to fill the dish to a third full. Poach for about 6 mins until just cooked.
In a pan, gently fry the onion, carrot, celery, and fennel. When these are soft add the garlic, lemon zest and wine.Bring to the boil; then reduce to a medium heat so that the wine reduces by half. Add the lentils and stock, bring to the boil and simmer for about 10 mins until the lentils are al dente. Finally add the juice and tarragon. Season to taste. To serve, place a piece of salmon on top of the lentils and drizzle with a little extra lemon juice.