Prepare the chicken by making sure it is all about the same thickness. Usually I will cut the breast horizontally into two thinner breast pieces. This ensures they cook uniformly and also helps the marinade penetrate the chicken fully.
When ready to cook, remove the chicken from marinade letting the excess drip off. Place directly on the grill and cook for 4-5 minutes per side, or until cooked through. This may vary depending on the thickness of the chicken. Remove from grill and let rest for 5 minutes. While the chicken rests, quickly heat the tortillas on the grill.