The pickled radish sometimes used in sushi rolls is takuan. It is made from daikon, the large white Japanese radish, and is usually recognizable by its yellow color, crisp texture, and sweet-sour, salty flavor.
Traditional takuan is prepared by hanging daikon to dry for several weeks before packing it in rice bran and salt. The radish then ferments for months, although many modern commercial versions use faster methods and may contain sugar or coloring. The pickle is commonly served as a side dish with Japanese meals and is also eaten as a snack.
In sushi, thin strips of takuan appear in rolls such as shinkomaki, which contains takuan alone, and torotaku-maki, which combines fatty tuna with takuan. It is often confused with gari, the thinly sliced pickled ginger served between sushi pieces. Tsukemono is not one particular pickle; it is the general Japanese category for pickled vegetables. Takuan is also called takuwan or takuan-zuke.