A question about Scandinavian cuisine

Brassica alba -- mustard -- is native to the Mediterranean, mentioned in the Bible, cited for medicinal use by Pythagoras and Hippocrates, sent by Alexander the Great to Darius III of Persia as a symbol of the strength and numbers of his army. It was introduced to Spain by Arab traders in the Middle Ages. (source, The Spice Book by Morris and Mackley)
That doesn't answer your question, but gives it some context. I think it's safe to say that mustard has been used in the kitchen for a long time in a lot of places, and the division between food and medicine was very close.

Thank you everyone. That pretty much answers my question. I came across an older recipe for a swedish soup that had mustard in it, and I wondered whether that was indeed a traditional recipe or more of an interpretation. Thougt about cardamom, which is loved so much there, and since it and mustard come from the same place, it made me wonder.

Just google "Swedish mustard" and you'll get a lot of hits, many touting their "traditional recipe." Swedish mustard is a little sweet. Mustard and dill sauce is commonly served with gravlax. And mustard seed is commonly used in lightly pickled cucumbers.

This response is off the top of my head, but mustard is indigenous to northern Europe. In Germany it is used in sausages or as a spice added to marinade for pickled beets, Sauerbraten and assorted meats, as well as for a condiment to accompany meats or sausages. I would suspect that it also found its way into traditional Scandinavian cuisines, but you may want to google 'Scandinavian herbals' to see if it was included in any of the earlier treatises on native plants. Perhaps also look for early recipes for pickled herring (or pickled vegetables) to see if mustard seeds were used. I think wild mustard is considered an invasive species today, so I wouldn't try planting any for research purposes!

Here in Denmark, mustard as a condiment is often used to accompany certain types of smørrebrød (the traditional open-faced sandwhiches, which are served on top of a buttered piece of rye bread). The mustard usually accompanies rullepølse (a type of sausage). Remoulade (which uses mustard) is also very, very popular, especially on fried fish and roast beef. And hot dogs, the all-time favorite midnight snack in Denmark, are almost always offered with mustard and ketchup.