Jomadam Kalguksu Hongdae Direct Branch in Seoul serves clam kalguksu and clam jjamppong kalguksu. The noodles are made in-house and the broth, with mussels, scallops and surf clams, is clean and cool without being harsh. The shop works for solo diners, dates and groups, and can be rented out. There is a wait at lunchtime.