A strawberry tart was a pastry dish from Earth. Tarts were similar to pies, except that the top was uncovered, and this one was made from strawberries.
When Seven of Nine spoke to her aunt, Irene Hansen, in the Astrometrics lab, Irene recalled how she had coaxed a young Seven out of a cupboard with a strawberry tart after she locked herself in there for having to stay with her. Seven replied she was fond of strawberries, and did not recall eating them as a child. (VOY: "Author, Author")