Hard to imagine a Midsommar party without these traditional foods. What is gravlax? Gravlax (or gravad-lax) is a dish of cured fish. Traditionally, the fish was salted and then buried in the cold ground and left to pickle/preserve in its own juices as the salt drew them out of the meat. Lacking a suitably chilly patch of permafrost, we use our fridge - and Marcus Samuelsson's recipe in Aquavit: And the New Scandinavian Cuisine. This book is dynamite. We received it for Christmas a few years ago and have absolutely LOVED every recipe we've tried. I highly recommend checking it out from your library and giving some of the dishes a go: the venison chops marinated in akvavit and juniper, with a berry chutney, is a particularly gorgeous and company-worthy dish.
Anyway, so you mix together salt, sugar, and cracked peppercorns (hence the morter and pestle; you want to crack, but not grind, the pepper), rub it into both sides of a beautiful skin-on cut of salmon (is that not a gorgeous piece of fish? I love living so near to Alaska), set it in a dish and sprinkle the remaining salt/sugar over, then cover the fish with fresh chopped dill.
It sits on the counter in a cool place for 6 hours, then goes into the fridge for 36:
When it's done, you simply rinse off the salt sludge and slice it up. We actually rinsed ours, then wrapped it in plastic wrap for another day until our party. This stops the pickling process before your salmon turns into jerky and as the meat has been cured, there's no problem wrapping it up for another day or two or three - even four, if there had been any kind of leftovers (there weren't; I barely got a scrap, myself).
And while on the subject of pickled fish, we also serve smorrebrod, a traditional open face sandwich, using this recipe from epicurious for a smorrebrod with herring in mustard sauce and pickled beets. I use Beth Hensberger's Bread Bible recipe for the Swedish Rye bread, and sneak in extra fennel, orange zest, and replace some of the water with extra molasses in mine. Then I bake it in many mini loaf pans so we can make cocktail-sized smorrebrod bites.