In a medium bowl, mix together the coarse salt, sugar and crushed peppercorns until well combined. This dry cure will draw out moisture from the salmon and gently season it.
Rinse the salmon fillet under cold running water and pat it completely dry with paper towels. Run your fingers along the flesh to check for any remaining pin bones and pull them out with kitchen tweezers.
Roughly chop the fresh dill. If you are using lemon zest, stir it into the salt and sugar mixture now so the citrus aroma infuses the cure.
Spread a thin, even layer of the salt and sugar mixture over the bottom of a glass or ceramic dish. Place the salmon skin‑side down on top. Cover the flesh completely with the remaining cure, pressing it gently, then add a generous layer of chopped dill on top.
Cover the dish tightly with plastic wrap. Place a weight on top, such as another smaller dish or a few cans, so the salmon is pressed evenly during curing.
Refrigerate the salmon for 24 to 48 hours. The longer it cures, the firmer the texture will be. About halfway through, pour off any liquid that has collected in the dish and re-cover.
When the curing time is up, lift the salmon from the dish, remove the dill and excess salt mixture, and briefly rinse it under a gentle stream of cold water. Pat completely dry with a clean paper towel.
Using a very sharp knife, slice the salmon on a slight diagonal into thin, wide slices, cutting down towards the skin without slicing through it. Serve the silky slices on bread, crackers or as part of an appetizer platter.