Naengmyeon originates from North Korea. The noodles are either made from buckwheat or potato starch, the former being Hamhung style and the latter, Pyongyang. The buckwheat noodles are extremely long and chewy and absolutely require prior cutting with food scissors before eating; otherwise it'd feel like you're trying to swallow a whole noodle nest. The Pyongyang style noodles are less chewy and can be easily bitten through; some people find the texture too brittle.
There are two basic varieties: bibim (mixed) naengmyeon and mul (water) naengmyeon. I rarely go for the bibim because I like the broth the mul version comes with. It's the taste of the soup that gets me salivating most of the time and I usually don't leave a single drop.
Pyongyang style mul naengmyeon:Noodles in broth with slices of Korean pear, cold boiled beef, green onions, red chili powder.
The notice from the restaurant declaring the reduction of fat, sodium and calories in their menu. Thus the 'healthy restaurant' designation from the Seocho district office. Such a good idea for the "well-being" conscious clientele.
P.S. Will post about Hamhung naengmyeon soon.