Not sure that many people from KC have been to Taco Diner in Highland Park, TX (a suburb of Dallas), but if you get the chance, you need to go. I was there in April and I'm still thinking of it.
Simple, fresh, super tasty asada tacos with a terrific asortment of salsas and relishes. Is there anything in KC like it? One of the guys I was with suggested the Mi Cocina is similar, but to me it's only in aesthetics.
If someone can suggest something like this place in KC, PLEASE DO!