Mind blowing isn't it? Check out the comic. I'll have more pics soon. He opens tomorrow and he's across from the KEB in hannam-dong (near Danguk University.) If you are taking the 110 bus from Sinsa, it'll stop right by there. If you are in a cab then ask them to take you to UN Village.
Naked Grill. English Spoken (fluently). Prices start at 4,000 won.
Here's a post on the Naked Chef Taco Truck in Seoul
Here is a map in the general direction. It's across from the KEB in Hannam-dong.