Add all of the marinade ingredients to a bowl; whisk until well-combined. Pour the marinade into a large, zip-top bag.
Add the chicken thighs to the bag, seal, and massage the bag to thoroughly coat the chicken in the marinade.
Cover and set aside to marinate for 2 hours in the fridge.
Preheat a grill to medium-high heat.
Once the grill is hot, arrange the chicken thighs on the grill grates. Let them cook for 5 to 7 minutes per side, or until golden-brown with dark grill marks. Chicken is done when the internal temperature registers at 165°F.
Remove from grill and set aside for a few minutes.
Serve the chicken thighs warm, with a drizzle of yogurt and sprinkling of chopped parsley (if desired).