dfw - El Pollo Regio
It appears to be covered in an Achiote Paste, which according to Wikipedia, "usually includes annatto, Mexican oregano, cumin, clove, cinnamon, black pepper, allspice, garlic, and salt. The annatto seeds dye the mixture red, and this gives the meat or vegetables it seasons a distinctive red hue."
I tried to re-create it myself many times, but ended up spending far more time and money than it took to just buy the darn thing, and I never even came close to getting it right. Also, there's something awesome about the way they chargrill it. Never could duplicate that either.
I did contemplate getting a job there just to get the recipe. :-)