There's a bunch of "authentic" Korean restaurants in the NE. When I say authentic, I mean most customers are Korean as are the waitresses who have a very hard time speaking english. I've been to Seoul Garden at 101 Washington Lane, which was a great Korean BBQ buffet.
I've drove by another called Che Ju Do at 716 Adams Ave and again I see mostly Korean customers with a Korean wait staff --even less English. They have a fixed price tasting menu with sashimi and live octopus! But that's over $100. They also have some dishes at about $30 (incl the live octopuses) it seems. However, there's no review of this place yet. A lot of money to risk on exploration.