Remove and discard skin from the chicken thighs. Wash thighs and add to the masala. Stir well. Cook chicken thighs for 10 minutes, until the chicken looks cooked on the outside. Add sour cream and water and stir well. Increase the heat to medium-high. When curry starts to boil, reduce the heat to medium, cover and cook for 15 minutes, stirring 2 or 3 times, until chicken is completely cooked. Poke the thighs with a knife. If the meat is still pink, cook for 5 more minutes. Remove and discard the cinnamon stick. Cool curry for at least half an hour.
Transfer cooled chicken to a mixing bowl. Peel chicken meat off the bones. Discard bones and stir chicken back into the curry. Just before serving, heat curry on medium heat until it starts to boil lightly. Stir in cilantro.
Turn on your stove exhaust fan. In a heavy-bottomed frying pan, heat cloves, black cardamom seeds, cumin seeds and cinnamon sticks on medium to high heat, stirring constantly. When the cumin seeds become a darker shade of brown, remove from the stove. Transfer the roasted spices to a bowl and cool for 20 minutes.
Place roasted spices, mace and nutmeg in a spice (or coffee) grinder and grind until the mixture has the consistency of store-bought ground black pepper. Can be used right away. Will also keep in an airtight container in a dark cupboard or drawer for up to 6 months.
