With a very sharp knife, trim the gray fat off the skin side of the salmon; it has a strong flavor. Slice the salmon as thinly as possible. Make the marinade: Put the lemon juice in a small bowl. Gradually whisk in the olive oil, then whisk in the fennel fronds. Season with salt and pepper. Arrange the salmon in an oiled dish large enough to hold the slices in a single layer. Scatter the celery over the fish, then spoon the marinade over all. Cover and refrigerate until the salmon is a little more than half cooked, which you can tell by the change in color from rosy orange to pale pink. It should take about 3 hours, depending on the thinness of the slices. To serve, divide the salmon among 6 plates, reserving the marinade. Put the sliced fennel in a bowl and drizzle with enough of the marinade to coat it lightly. Toss well, then taste and adjust the seasoning. Divide the fennel among the plates. Spoon a little extra marinade over the salmon. |