Porridge has a long history in Norway. In fact, it is the country's oldest warm dish, a mainstay of peasant diets since Viking times until the advent of the potato in the 1850s. Porridge was also considered a festive food, served most often at special occasions, or for Christmas. It could be 'risengrynsgrot,' a creamy rice porridge, or 'rommegrot,' a mixture of finely ground flour cooked in sour cream and topped with a generous amount of golden butter. Norwegian-American immigrants brought their own versions of the dish to America.