Karashi (芥子, 辛子, からし, or カラシ) is a type of mustard used as a condiment or as a seasoning in Japanese cuisine. Karashi is made from the crushed seeds of Brassica juncea and is usually sold in either powder or paste form. Karashi in powder form is prepared by mixing with lukewarm water to a paste and leaving it covered for a few minutes.
Karashi is often served with tonkatsu, oden, nattō, and shumai. It can be used as part of a dipping sauce when mixed with mayonnaise, called karashi mayonnaise or with vinegar and miso, called karashi su miso.