How adventurous are you? I took my Italian supplier to a local Korean bbq restaurant near Kangnam and he loved it. I wrote about this restaurant in a different thread, but I will give you the directions to the location.

The restaurant is called Bonga. It is located within walking distance from the Novotel Hotel in Kangnam. If you can find your way to Sinnonhyeon Subway station, take the #3 exit, walk north to the first alley then turn right. Next turn left at the first alley. This is Bongeunsa-ro 1-gil (name of street). This street is unofficially called Eating street, or Food Alley. There are tons of local restaurants on this street. Head north up the street. About half way up the street, you will see Bonga on your left side.

http://bornga.co.kr/bonga/store_deta...egion=&str_na=

Perhaps it might be easier to print that page out so you have a picture of what it looks like. Also if you get confused you can show it to anybody and they can point you in the right direction. Or you can put this address into Google Maps 서울 강남구 논현동 165-13 and it will take you there. I've tried it using Blackberry and iPhone and it is pretty accurate.

What to order? They have this marinated thin strips of beef.... so delicious! It is called Woo Samgyup.

http://bornga.co.kr/bonga/menu_woo3.asp

Page also shows how to cook and eat it wrapped with greens. You order it per person. A serving for one person may not be enough. I've had two by myself and was very full afterwards.

Want to try something more local? They have a dish called Chadol Doenjang Jjigae. Basically, a beef stew but you take part of it and mix it in with the rice and veggies. It becomes their version of Bibimbap (mixed rice).
http://bornga.co.kr/bonga/menu_chadol.asp

This location is open 24 hours. First floor has chairs and tables, but the second floor is a sit-on-floor type.

Best of luck, have fun.