Manufactured since the 1950s by the Swedish seafood company Abba, Kalles kaviar ("Kalle's caviar") is a smoothish paste made with slightly smoked cod roe, rapeseed oil, salt and other spices and preservatives.
In picture: a tube of Kalles kaviar and a traditional way of serving it with hard-boiled eggs on an open-faced sandwich.
Kalles kaviar is highly popular in Sweden and Finland. Although mainly used as a sandwich spread, the paste can also be used to flavour various dishes, like sauces, dips, oven casseroles, fish dishes, etc.
The paste has a piquant, salty taste reminiscent of smoked fish and fish roe, slightly similar to the Greek dipping sauce taramasalata. The original product (pictured above) is nowadays also available in many flavour variations (eg dill, hard-boiled eggs, cream cheese), as well as in lighter and milder tasting varieties.