|"Is this all real? Or has this been happening inside my head?"
The topic of this article is of a real-life subject that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
Bouillabaisse is a seafood stew which originated in southern France. It is traditionally composed of at least three different kinds of seafood. Bouillabaisse is a flavour of Bertie Bott's Every Flavour Beans.
During the Triwizard Tournament in 1994, this dish was served at Hogwarts School of Witchcraft and Wizardry, in order to make the visiting students from Beauxbatons feel at home. Seeing the stew for the first time, Ron Weasley wondered what it was, so Hermione Granger told him its name, and that she had tried it on the holiday to France she took with her parents the summer before her third year and had enjoyed it. Ron, finding the bouillabaisse unappetising, refused to try it, but when Fleur Delacour later came over to the Gryffindor table to ask if she could take the dish back to her own table, he told her he thought it was "excellent," presumably in an attempt to win her favour.