Daikon, the Japanese white radish

What it is

Daikon is a white radish, much bigger than ours: the name means "big root". In Japan over 90% of what's sold is aokubi, literally "green neck": the head of the daikon, which sticks out of the ground and turns green in the sun. It's about thirty centimetres long and weighs about a kilo. Then there are the record-breakers: Sakurajima daikon, from Kagoshima Prefecture, usually weighs around ten kilos; Moriguchi daikon, from Aichi Prefecture, is about 1.2 metres long.

The heat

Whole, it tastes of very little. The tingle comes when you grate or cut it: the cells break, and two substances that were kept apart meet and form an isothiocyanate, from the same family as those in mustard and wasabi. The hottest part is the tip, which forms up to ten times more than the head. The heat evaporates: grated at the last moment it bites harder; leave it to rest and it mellows. The season matters too: it's hotter in summer and sweeter in winter.

Where it comes from

It wasn't born in Japan. It's thought to come from the area between the Mediterranean and Central Asia and to have arrived by way of China, but nobody knows when. It's already in the Kojiki, the chronicle of 712: in a song attributed to Emperor Nintoku, his wife's white arms are compared to daikon roots, then called ōne. In the Edo period it was grown all over the country and a great many varieties appeared. It's also one of the seven herbs of spring, under the name suzushiro.

In ramen

It isn't a classic topping. In Japan you'll find it grated in the odd "mizore" ramen: that's the name for dishes with grated daikon, and it means "sleet". On a rich broth it adds freshness. Grate it at the last moment and put it to one side of the bowl. For a milder taste use the head; for more bite, the tip. If you like it crunchy, slice it raw, paper-thin. Here you'll find it in Asian grocery shops and some supermarkets.