Heat a large cast-iron skillet. In the meantime, dry the chicken thighs with kitchen paper and rub them with the spices on both sides.
Add the oil to the pan and swirl the skillet around to cover its bottom with oil. Slowly, add the chicken thighs to the pan, skin side down. Don't overcrowd the pan.
Turn the heat down to medium-low. Cook the chicken on the skin side for 10 to 12 minutes or until the skin is deeply golden. Don't move the chicken in the pan for the first 5 minutes or so or you might break the skin. Once the fat has rendered properly, you will be able to move the chicken around as you wish.
Turn the skillet on the stove, once or twice during this time, the skillet might get unevenly hot. If you use a gas stove top, move the skillet around a few times as well, as the flame often burns stronger on one side.
If you feel the skin turns too dark too quickly, adjust the temperature.
After 9-10 minutes check the color of the skin, it should be deeply golden. Flip the chicken and continue cooking for another 15 minutes, moving the skillet and the meat a few times in between.
Check if the chicken is cooked through with a meat thermometer, the internal temperature should be of 74-77 degrees Celsius/ 165-170 degrees Fahrenheit. If you don't have a thermometer, make a cut with a small sharp knife near the bone, the meat should be completely cooked through, no signs of red or pink. If the chicken thighs are on the larger side, you might need to increase the cooking time slightly. Give it 3-5 more minutes and check again.