Whisk yoghurt in a large bowl, add the remaining ingredients and mix well. Rub the chicken pieces with this mixture. Keep aside for 3.5 hours. Preheat the oven to 180ºC . Skewer the marinated tikka at least an inch apart. Keep a tray underneath to collect the drippings. Roast in a moderately hot tandoor for 6-7 minutes, basting at least once. In a charcoal grill, for about the same time, basting once. In a pre-heated oven, roast the tikka for 8-10 minutes, basting at least twice. Make sure that the chicken does not touch the sides or the bottom of the oven.