Mix all ingredients except the chicken thighs together in a bowl. Once mixed well, add in the chicken and coat all the pieces well.
Cover the bowl and refrigerate - or pour the contents in a ziplock bag and refrigerate at least 24 hours.
Take the chicken out and place into a colander to drain off the yogurt marinade. You want to remove as much of the marinade as possible by wiping it off.
Spray your grill grates with some oil.
Turn on your BBQ grill and get to a nice hot temperature.
Grill the chicken about 7 minutes a side until they are cooked through.
Remove chicken, cover in foil and let rest for 5 minutes before serving.
Serve warm with naan bread
Garnish with lemons, parsley, sumac and red pepper flakes.