Biryani is not a dish — it's a world view. Every region of Pakistan and India has its own version: Karachi's spicier, oil-forward style; Hyderabadi dum biryani with saffron and kewra water; Lucknowi biryani with its more delicate spicing. This recipe is rooted in the dum tradition — cooking the half-done rice layered over marinated chicken in a sealed pot, so the steam does the work and every grain absorbs flavour from below and above.
The secret that most recipes skip: the chicken must be marinated for at least 4 hours, and the rice must only be 70% cooked before it goes into the pot. If either of these is wrong, no amount of technique will save you.