Somen

Somen is the thinnest Japanese wheat noodle: under Japanese labelling rules, dried noodles under 1.3 mm in diameter are called somen. The dough is wheat flour, water and salt, kneaded without alkali, so the noodle is white rather than yellow like ramen noodles. In dough it is kin to udon and hiyamugi: the same wheat dough, only thinner.

What separates somen from udon and hiyamugi is thickness, not dough. For hand-stretched tenobe noodles the limit is different: anything thinner than 1.7 mm can be sold as somen or hiyamugi.

The best-known somen is Miwa from Nara Prefecture. According to its entry in the Japanese geographical indications register, the dough of flour, salt and water is stretched into strips and left to mature, then repeatedly twisted and drawn into fine threads while edible oil is applied. The noodles are dried to no more than 13.5 % moisture and cut to length. Machines have taken over some of the manual steps, but hand-drawing survives. The texture is firm, the Japanese 'koshi', close to al dente: the elasticity lets the threads be drawn extremely thin without going soggy after boiling.

Miwa's history, says the same register, goes back about 1,300 years to Omiwa Shrine, where noodle-making reportedly began to help people through famine and plague. A document of 1754 praises Miwa's snow-white threads that stay firm in boiling water. Every 5 February the shrine holds the Bokujo-sai ritual, which forecasts the price of somen for the new season. Since 1965 production has spread across the whole of Nara Prefecture.

Why it matters to you. Somen contains wheat and therefore gluten; in Japan wheat is a mandatory allergen on labels. The name on a Japanese pack tells you the diameter, and the word 'tenobe' means hand-stretched.