It is traditional food of Busan of Korea.
When Korean war was broke out, refugges made and ate it
because rice was too expensive. In Busan, it was difficult to get buckwheat
which is ingredient of buckwhet noodle. So instead of buckwheat, people
mixed wheat flour with potato starch and sweet potato starch.
These days, people eat it with some vegetables and make various wheat flour noodles.
In summer, people like cool and clean taste of its soup.