Presoak the rice in hot water and salt for about an hour before cooking. Cut up the onion in large pieces. Wash and devein the chicken pieces, put them in a pot with some water, add the onion, turmeric, salt and a touch of saffron and let it cook until the meat softens. Take it out, drain it and set aside.
In a medium size pot, half filled with water, boil the rice for a few minutes, until the rice is half crunchy half soft when you chew on it. Take it out, drain it and set aside. You may want to wash off the rice in a stringer, if you used excessive amounts of salt to soak the rice.
In a bowl, mix the egg yokes and yogurt and beat it until it has a smooth texture. Mix in about a cup full of cooked rice.
In a medium size pot, pour half of the cooking oil in the bottom of the pot, evenly pour in the egg-yoke/yogurt mixture in the bottom, place the chicken pieces on top of it and top it up loosely with the remainder of the boiled rice. Sprinkle the remainder of the oil on top of it, close the lid, put the heat setting at high for a minute or so until the rice starts steaming.
Turn the heat setting to low and let it cook for about an hour and a half to two hours. The lower the heat and the longer the cooking time, the crustier and darker the bottom layer becomes. Careful not to burn it.