I’ve heard some really nice things about Taco Rico in Gangnam, particularly about being the real thing when it comes to Mexican food in Korea. Sadly I have no clue because every time that I’ve tried to eat there, they haven’t been open even during its stated operating hours.
Taco Rico is located in Gangnam. Go straight out of Exit 8. Turn left at the GS25. Walk straight. It’ll be the small red restaurant on the left.