Peel the cucumber, leaving every other strip of green. Cut it into slices. Powder it with fine salt. Leave to disgorge for 15 minutes.
Boil the vinegar with the sugar. Sponge the cucumber slices. Drizzle them with boiling vinegar. Let cool. Add the cream.
Pass the salmon fillet under cold water, quickly enough so that it is not soaked with water. Pat it up with a paper towel.
Oil it lightly, insisting on the skin side. Place it on a wire rack or baking sheet, skin side down. Place the grate or griddle in the fireplace above the ash-covered embers. Sprinkle the fish with fleur de sel.
Cook for about 10 to 15 minutes.
Arrange the salmon on a serving platter, season with pepper. Decorate it with dill and lemon slices. Serve the cucumber as a side dish.
You can do the same using a plancha.
