Mix the sour cream, mayonnaise, caraway and beetroot in a bowl that is large enough to contain all the ingredients. Fold in the whole herring fillets.
Cover and leave to stand in the fridge for a couple of hours to allow the tastes to meld.
500 g. (18 oz.) fillet of salt herring, whole pieces 2 dl. (6,8 fl. oz.) sour cream 1 dl. (3,4 fl. oz.) mayonnaise 2 tsp. caraway, slightly crushed 3 tbs. finely chopped pickled beetroot 2 tbs. finely chopped onion