Combine the salt, dill, orange and lime zests, pepper, and vodka in a small bowl and mix thoroughly.
Place the salmon, skin side down, on several large sheets of plastic wrap, and pack the salt curing mixture over the entire cut of the salmon. Press the mixture firmly onto the fish, wrap tightly in the plastic, and place, skin side up, on a baking sheet. Place something heavy, like a large iron skillet, on top to help infuse the salmon with the mixture. Refrigerate for 24 hours.
Remove the salmon from the refrigerator and brush the salt off. Rinse thoroughly under cold running water to remove the cure. Sprinkle the salmon with the sugar and pack it in firmly with your hands. Rewrap in plastic, place on a baking sheet, and refrigerate for at least 1 week before serving. (The gravlax will keep up to two weeks, well wrapped and refrigerated.)
To serve, unwrap the gravlax and using a long, very sharp knife, slice diagonally in paper-thin slices and place on a platter with toast points. Set out small dishes of capers, chopped red onions, dill, hard-boiled egg whites, and hard-boiled egg yolks for accompaniments.
Yield: about 20 servings