Sprinkle the salmon with salt. Place a couple sprigs of fresh dill in a skillet, add a cup of water (or half water, half white wine), bring to a simmer and add the salmon filet, skin side down.
Cover and simmer for 7-10 minutes, or until the edge flakes with a fork. If you want to make it ahead, cool and refrigerate for up to two days.
Meanwhile, whisk together the dressing ingredients, adding a spoonful of water if it seems too thick.
Arrange lettuce leaves on each plate and top with chopped cucumber and flaked salmon.
Chop the last sprig of dill and sprinkle it over top.