If you visit Seoul I'd recommend to eat one meal at this market, it's located in Jogno area and is called Gwangjang Sijang (Gwangjang market).
They also sell lots of traditional stuff too, but the food really attracts!!
We had dinner here one day, we jumped between places. The most famous dish is Mungbean sprout pancake. I prefer the neutral one, but my darling liked the seafood one.
We also had some ddeokbokki there, the pancake is big so be aware before buying lots, it might fill you up ^^