A cornichon is a small, tart pickled cucumber made from a young, slender cucumber (sometimes called a gherkin) picked while still tiny and pickled in vinegar with herbs and spices. The name is French for 'little horn,' describing its curved shape; French pickling of small cucumbers dates back to at least the 17th century, with cultivation centered on coastal regions like Brittany and Normandy.
Cornichons are a classic garnish for charcuterie boards, pâtés, and terrines, and an ingredient in sauces like gribiche. Their tartness and crunch also pair well with rich, fatty foods, and they're used as a condiment for sandwiches and burgers outside France. They should not be confused with standard dill or bread-and-butter pickles, which use larger cucumbers and different brines.