Make chicken marinade by combining all marinade ingredients in a large ziplock bag. Add chicken and shake/rub it around to make sure the chicken is well coated. Refrigerate for at least 2-3 hours or up to overnight. (The longer, the better.)
Cook for about 4-5 minutes on each side, or until chicken is cooked through. Transfer to a plate, cover with foil and allow the chicken to rest for five minutes.
Layer chopped chicken on a corn (or flour) tortilla and top with desired toppings.
I have found chipotle powder in the bulk foods section at Winco, but if you can't find it or the ancho chile powder, a good substitute is 1/2 tablespoon each of smoked paprika (make sure it's smoked), cumin and cayenne pepper.
If you're worried about too much "heat" from the chipotle powder, you can use the lesser amount. If you end up using the substitute spices listed, then just use less cayenne pepper but still the listed amount for the cumin and smoked paprika.
To make pico, I just chop a few roma tomatoes, a little bit of chopped red onion (I don't do a ton because I think it gets too over-powering, maybe a couple tablespoons), a handful of cilantro, chopped, half of a jalpeno finely chopped, and salt to taste. I really don't even measure. I just taste it and add what I think it needs.