In a large bowl, combine all the ingredients for the marinade, along with a good few pinches of salt and some pepper. Add the chicken thighs and mix everything together. Cover and chill overnight.
Light a lidded barbecue, then let the flames die down. Once the coals have turned ashen, mound them up on one side. Thread the chicken thighs onto 2 metal skewers – so that both skewers go through each piece of meat – packing the thighs down so that they are really compact. Place the chicken kebab on the side without any coals underneath. Pop the lid down and cook for 45-55 mins, turning regularly, or until cooked through – prise the chicken pieces apart in the centre to check this. Cover the chicken with foil and leave to rest for 20 mins before slicing. (If cooking in the oven, heat to 200C/180C fan/gas 6. Rest a wire rack over a roasting tin and place the chicken on top. Cook for 45-55 mins or until cooked through.)
Slice strips of chicken from the kebab and stuff into pittas, warmed on the barbecue. Serve with Dill yogurt sauce, tomato, red onion & cucumber salad, and crunchy lettuce.