Wash and soak the basmati rice in water for 20 minutes.
Bring 3 liters of water to a boil in a large vessel. Add 1 teaspoon cooking oil and 1 teaspoon salt.
Add the soaked and drained rice, stir gently, and cook for 3 to 5 minutes until the rice is just done.
Drain the water immediately and spread the rice on a large plate to cool.
In a deep-bottomed pan, heat oil on medium flame. Add 1 sliced onion and fry until brown. Remove and set aside for garnishing and layering.
Clean and wash the chicken thoroughly.
In a mixing bowl, marinate the chicken with thick curd, red chili powder, turmeric powder, and salt. Marinate for at least 30 minutes.
In a large pan, heat oil on medium flame. Add the remaining sliced onions and sauté for 3 minutes until translucent.
Add ginger-garlic paste and sauté until the raw smell goes away.
Add slit green chilies and sauté for a minute.
Add chopped tomatoes and sauté until they turn mushy.
Add red chili powder, coriander powder, and salt. Sauté for about 2 minutes.
Add 3 tablespoons each of chopped coriander and mint leaves and mix well.
Add the marinated chicken and cook until fully done. If there's excess water, increase the flame to thicken the masala until it coats the chicken.
In a large wide, deep vessel, spread ghee to coat the bottom and sides. Reduce the flame to low.
Add 2 full tablespoons of thick chicken biryani masala and spread it at the bottom.
Add a layer of cooked basmati rice over the chicken masala and gently spread to cover.
Repeat the layering process until all rice and chicken are used up.
Sprinkle coriander and mint leaves, and fried onions on top.
Close with a lid, place a heavy weight on top, and cook on low flame for 10 minutes.
Scoop out the Chicken Dum Biryani from the edges of the pan without breaking the rice grains.
Serve with pickled onions, Burani Raita, and Mirchi Ka Salan.