How to Make It
In a small bowl, combine the salt, sugar and peppercorns. Rub a handful of the seasoning mixture on both sides of the salmon fillet. Set the salmon in a glass or ceramic dish, skin side down, and sprinkle the rest of the seasoning mixture on top. Place the bunches of dill on the salmon and cover with plastic wrap. Let stand at room temperature for 6 hours, then refrigerate for 24 hours.
Scrape off the dill and seasonings and pat the fish dry. Using a long sharp knife, thinly slice the salmon fillet on the diagonal; do not slice through the skin. Cut off the gray triangle at the bottom of each slice. Arrange the salmon on a large platter, overlapping the slices slightly. Cover tightly with plastic wrap and refrigerate for up to 6 hours.
Cut the salmon skin crosswise into 12 strips. Set a large cast-iron skillet over moderately high heat. When the pan is hot, add the salmon-skin strips and fry until lightly browned, about 45 seconds per side. Drain on paper towels.
Set a dill sprig in the center of each strip of salmon skin and roll up the strips. Garnish the gravlax platter with the rolls and serve with lemon wedges.