Prepare Marinade: In a medium size mixing bowl combine the ingredients for the marinade. Whisk together.
Marinate Chicken: Add the chicken and submerge in the marinade. Cover and place in refrigerator to marinate 2-4 hours (over marinating can cause mushy chicken).
Preheat: Preheat grill to 425℉.
Remove chicken from the marinade and pat dry.
Grill: Place the chicken over direct heat on the grill and cook for 3 minutes then flip the chicken. Cook an additional 3 minutes.
Move the chicken to more indirect heat on the grill, cover and cook for an additional 5-7 minutes until the chicken reaches an internal temperature of 160°F in the thickest part.
Allow the chicken to rest (the internal temperature will continue to rise to 165°F). After resting the chicken can be chopped.
Heat Tortillas: Prepare the corn tortillas by heating to soften. Use a comal or skillet over medium heat, briefly heat the tortillas for 15-20 seconds on each side. Or place tortillas on a heat safe plate and microwave for 30 seconds.
Serve: Layer the tortillas if wanted, using two tortillas and filling with the diced chicken. Top with diced onion and cilantro or additional toppings as desired.