Mussels with tomato vinaigrette

Dry the salmon with kitchen paper and season with salt. Heat the canola oil in a large frying pan and fry the salmon, skin-side up first. Turn, then add the butter and fry until the skin is crispy and fish is just cooked. Add the lemon juice and keep warm.
Serve the salmon topped with the wilted lettuce and the crème fraîche on the side.
To make the wilted lettuce salad, remove the outer leaves of the lettuce. Slice the head in half lengthways and remove the thick part of the stem. Cut the lettuce into quarters, then halve again.
Melt the butter in a large frying pan and sauté the spring onions until soft, but not brown. Add the stock and wine or verjuice and bring to a boil, then add the peas and lettuce. Cover and cook until the peas are bright green.
Season with salt if necessary.