Soba

thin noodles made from buckwheat, or a combination of buckwheat and wheat flours 

Usage and cultural significance

According to https://en.wikipedia.org/wiki/Soba

 

"Soba is a good nutritional addition to a diet reliant on white rice and wheat flour. Thiamine, missing from white rice, is present in soba. Soba contains all eight essential amino acids, including lysine, which is lacking in wheat flour. The tradition of eating soba arose in the Edo period".