Remove any bones from the fillet with tweezers, long nosed pliers or by trapping them between the point of a small vegetable knife and your thumb.
With a sharp filleting knife or carving knife cut the salmon into 12 slices about 5mm/¼in thick. Cut on the slant down to the skin angling your knife at about 45 degrees so that you can get wider slices.
Brush a grilling tray with oil and put in the 12 escalopes of salmon. Brush lightly with oil and season with a little salt.
preheat the grill to high and put four large plates in the oven to warm. Place the fish stock, half the cream and vermouth in a pan and boil rapidly to reduce by three-quarters. Meanwhile, wash and pick the stalks from the sorrel. Slice the leaves very thinly. When the fish stock has reduced, add the rest of the cream, the butter and the lemon juice. Reduce a little more then stir in all but a pinch of the sorrel.
Grill the escalopes for about 1 minute. Pour the sauce over the warm plates. Carefully lift the escalopes from the grilling tray with a pallet knife and lay them on the plates, slightly overlapping. Sprinkle over a little chopped sorrel and serve.
