A relish is a cooked, pickled, chopped vegetable or fruit food item which is typically used as a condiment.
The item generally consists of discernible vegetable or fruit pieces in a sauce, although the sauce is subordinate in character to the vegetable or fruit pieces. It might consist of a single type of vegetable or fruit, or a combination of these. These fruits or vegetables might be coarsely or finely chopped, but generally a relish is not as smooth as a sauce-type condiment, such as ketchup. The overall taste sensation might be sweet or savory, hot or mild, but it is always a strong flavor that complements or adds to the primary food item with which it is served.
Relish probably came about from the need to preserve vegetables in the winter. Chutney might be considered a type of relish. India where the preparation originated from, generally includes either vegetables, herbs or fruits.
In the United States, the most common commercially available relishes are made from pickled cucumbers and are known in the food trade as pickle relishes. Two variants of this are hamburger relish (pickle relish in a ketchup base or sauce) and hotdog relish (pickle relish in a mustard base or sauce). Other readily available commercial relishes in the United States include corn (maize) relish. A notable relish is the Gentleman’s Relish, which was invented in 1828 by John Osborn and contains spiced anchovy. It is traditionally spread sparingly atop unsalted butter on toast.
You can find authentic Japanese Relish on many Japanese Restaurants in Los Angeles.