I finally found really good Mexican in Seoul. The place is Dos Tacos. Two Korean guys traveled to Mexico for a few years to study the art of the taco and I gotta say both their pork and beef were spot on good.
Also, the hot sauce was bomb because Koreans know spice.
I went to a brunch place called Flying Pan. It was actually good, like passable if it was in NY. I feel like they meant to call it Frying Pan instead of Flying Pan but can't pronounce the R.