In Wassup Man, Park Joon-hyung ran a full eating tour — from tteokbokki to slurping jjajangmyeon — through Tongin Market in Seoul's Seochon. That episode, working briskly through the market's alley food, came from here.
Tongin Market is a traditional market in Seochon, west of Gyeongbokgung Palace, famous for its 'brass-coin lunchbox' — you buy brass coins and fill a lunchbox with market side dishes — and for soy- and gochujang-based oil tteokbokki. One brass coin is 500 won; exchange coins at the lunchbox cafe and have fun choosing dishes around the market.
Pair it with Gyeongbokgung, the Seochon alleys and the Tongui-dong cafe street for a walkable day. Note that the lunchbox cafe runs only from late morning to afternoon and is closed on Mondays.
Please re-check opening hours and access on official channels before visiting. Some links may be affiliate links.