Sharp heat that rushes up the nose rather than burning the mouth. Sold as green paste in tubes for sushi, often made from horseradish, and as mustard powder, which seasons cold noodles and a Beijing cabbage dish.
In Chinese, 芥末 covers both Western yellow mustard and Japanese wasabi. For clarity, wasabi is sometimes called 山葵 or 绿芥末 (green mustard), while yellow mustard is 黄芥末.