A sac is used with a cast iron pot

Pictured above is a "sac", which is a special bell shaped lid used with a cast iron pot. It's specially shaped to hold hot coals, similar to a camp oven.

Note that the pot is partially buried in hot ashes, in which it slow cooks.

It's a popular method in Turkey, Slovenia, Croatia, Montenegro, Serbia, and Bosnia.

Usually meat and potatoes, or meat and veggies, or bread is cooked under a sac.

Most popular is roasted lamb.

I can't find any specific recipes yet, but some photos are here and here.