Preheat the oven to 350 degrees . Place the lentils in a medium saucepan with 3 cups water. Bring to a boil and cook over medium-low heat until just tender but with a bite remaining, 8 to 10 minutes; drain.
Place the salmon in a shallow, ovenproof skillet with the wine, bay leaves, dill and parsley sprigs and sliced lemon; season with salt and pepper. Add enough water to just come to the top of the fish, but do not cover. Bring to a boil, then transfer the salmon to the oven and poach until opaque, about 15 minutes.
In a large bowl, combine the lemon juice with the mustard. Whisk in the EVOO and season with salt and pepper. Add the chopped dill and parsley, the onion, cucumber and lentils; toss to combine.
Remove the fish from the poaching liquid. Serve the salmon fillets with the lentil salad, rolls and butter.