If you're near COEX Mall in Seoul, you may want to check out these restaurants and their most popular dish:
Bongchu Jjimdak: Bongchu Jjimdak is a popular Korean restaurant near COEX Mall known for its spicy braised chicken dish. The chicken is cooked with vegetables and a spicy sauce made with gochujang, a traditional Korean chili paste. The dish is served with rice cakes, potatoes, and other vegetables. Bongchu Jjimdak is a great place to go if you enjoy spicy food and want to try a classic Korean dish.

https://danielfooddiary.com/2016/01/12/bongchu/
Jungsik: Jungsik is a highly regarded restaurant near COEX Mall that serves modern Korean cuisine. Their innovative dishes blend traditional Korean ingredients and cooking techniques with modern flavors and presentation. Jungsik is a great place to go if you want to experience the essence of Korean cuisine in a contemporary and refined setting.

SMT Seoul: SMT Seoul is a popular Korean BBQ restaurant near COEX Mall. Their specialty is their succulent and flavorful grilled meats, which are served with a variety of side dishes such as kimchi and pickled vegetables. The restaurant has a modern and stylish decor, making it a great place to enjoy a night out with friends or family.

You can also try these restaurants known for their popular dishes:
These are just some of the many restaurants near Coex Mall. It is recommended to use KakaoMap or Naver to look for the nearest spot.