Traditionally the meat is hung above the rice in an underground pit oven so its fat and juices drip straight down and slow-cook the rice below it — the rice is basically basted by the meat suspended over it.
Mandi is rice and whole cuts of lamb or chicken cooked low and slow — classically buried in a covered underground pit with hot coals — so the meat turns fall-apart tender and the rice underneath soaks up its dripping juices and smoke. Jeddah's old-town stalls and Yemeni-run restaurants pile it high on shared metal trays for takeaway.