The history of Olasagasti started with a Sicilian immigrant who ended up in Getaria in Basque Country and married a local Basque woman with the last name of Olasagasti. Their grandchild started this company in 1929 and named it after his grandmother.

Onions are slowly sauteed until soft and sweet and finished with a little white wine and vinegar before adding the tuna loin. A tasty meal on its own.