Cube sweet potato and add to boiling pan of water. Boil until soft, about 15 minutes, then drain, add nutmeg, mash and season.
Meanwhile, mix cayenne pepper, coriander and paprika, and rub in to steak. Heat the oil in a pan, and add steak, sear on both sides for 1 minute, then turn down to medium heat
Cover and cook for 3 minutes, or to preference
Add chopped broccoli and cook for a further minute covered