This Swedish specialty of raw salmon cured in a salt-sugar-dill mixture is prized around the world. It's sliced paper-thin and served on dark bread as an appetizer, on an open-faced sandwich or as part of a smorgasbord, often accompanied by a dill-mustard sauce. Gravlax can usually be found in gourmet markets or specialty fish markets. It can be stored, tightly wrapped, in the refrigerator for up to a week.