I have fond memories of Swedish food. Great cold cuts, salmon, herring, and trout in a variety of ways and with a variety of sauces. Smoked or salted raw fish, especially gravlax (raw, cured salmon) by itself is fantastic. Adding sauces that are completely surprising make them amazing.
And then there is lingonberry gelée (jam), an incredible condiment to any game meat (reindeer anyone?). I had game dishes as part of a smörgåsbord (table with lots of different dishes) and lingonberry gelée's sweetness really enhances the game.
As kids, in Berlin, we grew up eating knäckebröd because it is so healthy (and extremely crispy which made it fun to break and eat). I remember learning to butter the bread very carefully so it would not break.
At least as necessary in Sweden is a comment about restaurants and cafeterias. Almost all restaurants are great looking, bright, and minimalistic (Ikea is a pretty good reflection of Swedish design concepts). Even offices are bright and sun-streaked (according to building codes, every office has to have natural light) which extends to company cafeterias. A long time ago, I visited the Ericcson headquarters near Stockholm, and we had lunch in their cafeteria. Never been to a cafeteria with better food than theirs (take that Google and Porsche)!
While there is not one specific main course I remember from my frequent trips to Sweden, I fondly remember having amazing appetizers, great main courses, and nice desserts everywhere.