To make the chicken marinade: Simply mix all of the ingredients except the chicken in a bowl. Add the chicken thighs and massage them with the marinade.
Place the marinated chicken in a ziplock bag and refrigerator up to overnight. The chicken will absorb all the flavors of the marinade, resulting in a very juicy-delicious chicken!
Meanwhile, make the Tzatziki: Mix all the ingredients in a bowl. Keep in the refrigerator until you serve the gyros.
When ready to make the Gyros: start your Spark and set it to 650°F. If working with fresh pita dough, grill until you get a nice color on one side, then flip it and do the same for the other side. If using store bought pitas, follow the same method but grill for a shorter amount of time just until warm. Wrap the pitas with a towel to keep them warm and sexy.
Add the marinated chicken to the grill, shaking off some of the marinade on the way to the grill, and grill on each side for about 3-4 minutes, until cooked through. Slice it up for the Gyro.
Build the GYRO!!! Take one pita, spread two tablespoons of Tzatziki, add sliced tomato, some sliced red onion, the chicken, and finish with another teaspoon of Tzatziki.