Light a grill or heat a grill pan. In a bowl, mix the preserved lemon with the shallot, parsley, and 1 tablespoon each of the oil and lemon juice. Using a knife, make 1-inch-deep slits in the salmon skin, 1 inch apart. Rub the preserved lemon mixture into the slits. Rub the remaining 2 tablespoons of oil all over the salmon, then drizzle the fish with the remaining 2 tablespoons of lemon juice; season with salt and white pepper.

Grill the salmon, skin side down, over moderate heat until the skin is lightly charred and crisp, 5 minutes. Turn the salmon and grill until just cooked through, 3 to 4 minutes longer. Transfer the fish to a platter, skin side up. Scatter the olives over the fish. Cut the salmon crosswise into 6 pieces and serve.

The seasoned salmon can be refrigerated for up to 4 hours.

Preserved lemons are a Moroccan ingredient made from lemons that have been cured in lemon juice and salt. Look for them at specialty-food shops.