Hi, new member here, recent transplant from Kansas City to Chicago. Geo invited me, as he was my professor for a time and a fellow foodie.
I have to say, as soon as I heard about the concept of putting korean ingredients in a taco format, I thought it was brilliant and hoped to see a wave. As a native Kansas Citian, I'm amazed that korean bbq isn't more popular there, and excited to be somewhere that it's better appreciated.
I've tried them at "Del Seoul" in Lincoln Park, and they were excellent. I had Kalbi Taco's, and now I can't remember if the other one I tried was Spicy BBQ Pork or (less likely) Spicy BBQ Chicken. I really need to go back and find out.

I'm really interested in exploring the rest of their (still growing) menu.
http://www.delseoul.comI also tried them at "Taco Chino" (4712 N Kimball Avenue), which is really a Mexican restaurant that has also added three different Korean tacos. I guess the flavors weren't really suited to me, but they might be better to someone else. (Pork Kimchi, bulgogi, and I believe Kalbi(?) were the options). I tried them all, but they just fell short for some reason. Especially when you consider they're the same price as Del Seoul's. Note that they don't have them on the menu board, nor on the paper menu. The only way you know that they serve them as you walk in is that they're depicted on the shopfront window.
I think that there are at least one or two other places that have dishes that fuse Korean and Mexican cuisine, but I don't recall where I saw that.