Gravlax originated in medieval Scandinavia as a lightly salted, pressed form of salmon that was preserved by fermentation and had a strong smell. By the 18th century, it had evolved into a lightly salted and pressed but unfermented dish. This new gravlax had a subtle flavor, a dense, silken texture that makes it possible to cut very thin slices, and a glistening, translucent appearance. This refined version of gravlax has become popular in many countries.
Modern recipes for gravlax call for widely varying amounts of salt, sugar, and time. Fresh dill is now the standard flavoring, probably a domestic replacement for the original pine needles, which are a delightful alternative. The salt, sugar, and flavoring are sprinkled evenly over all surfaces of salmon fillets, the fillets are weighted down, and the container refrigerated for one to four days. The weighting provides intimate contact between flesh and flavorings, presses excess fluid from the fish, and compacts the flesh. Salt dissolves the major contracting protein myosin in the muscle fibers, and thus gives the flesh its compact tenderness.