Seongsu-dong tonkatsu restaurant with sweet potato croquette: Kosi
Kosi Seongsu Branch is a tonkatsu and udon restaurant on Sangwon 1-gil in Seongsu-dong, Seoul, near Exit 6 of Ttukseom Station. On an early-evening visit, the half-and-half katsu set cost 13,500 won with udon added for 3,000 won, plus a sweet potato cheese croquette from the review event. Both the cheese katsu and the plain katsu were tender under crisp breading, and the window counter makes Kosi Seongsu Branch an easy choice for solo diners.