The fire really had made quick work of the juice boxes. I reluctantly pulled the first, charred hunk of foil out of the fire and gingerly tried to unwrap it. The buns were charred. Actually I think charred might not be accurate. The buns were cremated. Hardened little nubs of charcoal. It was not edible.
My error? On the original camp out we put the juice cartons in hot coals, not a hot fire. Apparently this makes a huge difference.
Good to know.