Thinly slice the leek and fennel.
Heat the oil and gently sauté them for 5 minutes. Add the juice of half a lemon and keep cooking, under a lid and over low heat, for another 5 minutes or so, until tender.
Add the chopped dill and put the salmon filet on top. Add the stock or wine. Season to taste.
Squeeze the other half of lemon juice over the fish.
Cover and sauté for 5-8 minutes, depending on the thickness of the fish.
Serve on a bed of pea shoots or watercress with some dill scattered over the fish.