Avec

Avec: a word meaning "with" in Quirmian but which takes on, in Morporkian, the collective of all the things that might be added to whatever plain, wholesome foodstuff your meal started as. Quirmian chefs, and their imitators in Ankh-Morpork, often advertise dishes as "something avec something", but real down-to-earth Morporkians tend to be wary of avec in their meals.
Fred Colon would not object to a heap of slumpie "avec beurre", though.