The Tazawakocho Nameko JA agricultural cooperative is located to the north west of Honshu island.
Its main activity is producing tonburi.

These are seeds from the Houkigi or Koshia scoparia plant, a regional specialty from Akita prefecture.
The pearled black and green seeds of about 1 to 2 mm in diameter are similar to fish eggs, with a very crunchy texture and a broccoli and artichoke smell.
Akita is a mountainous region but the Houkigi (Koshia scoparia) is mainly grown in the valleys. It is harvested in September during the typhoon season. The farmers must pay great attention to the time of harvesting because a typhoon can blow all the seeds away.
Tonburi production is different depending on the producer or family: each one jealously guarding their secret. Generally the seeds are boiled and then soaked. The outside layer is removed by rubbing the seeds between the hands.
These movements are repeated several times, which has the effect of heating the seed and changing the original texture.
JA Tazawakocho Nameko cooperative has put in place a new method without heating. The result? : optimisation of the firm and sensual texture of the seed in the mouth.

The Kochia scoparia is hand harvested by sickle. Then it is sun dried and threshed to remove the seeds.

The seeds are then soaked for 24 hours to make them swell and then mechanically peeled, washed, strained and finally soaked again with a little acetic acid to reduce the acidity.
Then they are drained and all the remains (skin, foreign bodies) are removed with tweezers!
Finally the seeds are put in preserving jars which here, are traditionally steam sterilised in a boiler. The sterilisation process cannot use high pressure as it will destroy the special tonburi texture.

Tonburi shouldn't be heated because it will lose its crunchy texture.
If any seasoning is needed it is done at the last moment.

Until 1975 tonburi was only consumed by the farmers who grew it.
The Houkigi (Koshia scoparia) plant was imported from China during the Heian period (794-1192) where it had been used for more than 3000 years as a medicinal plant. In fact the dried seeds are fortifying, rejuvenating and diuretic. In Japan, during the Heian period, only noble families grew it for medicinal purposes. Writings from the Edo period (1603-1868) state that Houkigi seeds were used in pharmacopoeia and that the stems were used to make brooms ( Houki in Japanese).