If you are a little more adventurous and have the time, you can go to Floresta. There are a few authentic Korean places there. Some are traditional soup places, while a couple are the Korean BBQ. You can google for 싱글벙글 Singul Bongul Restaurant on Moron Street, and there are 2-3 others within the same couple blocks. You probably need a car or take the bus to get there. It is fairly safe (Korean guys are big ;-) but of course, always take your precautions. By the way, you can go there at "American" dinner hours and there will be food already as Koreans do eat earlier than Argentinians.
I´m not Korean but have lived in Asia and the SF Bay Area, and can say that these Korean places are pretty authentic.