Preheat the barbecue flat-plate or char-grill plate to hot. Lightly score the inside of the butterflied lamb leg in a criss-cross fashion. Rub the sumac over the lamb, then brush or spray lightly with oil and season with salt and pepper.
Place the lamb on the barbecue, reduce heat to moderately-hot. Cook the first side of the lamb for 20 minutes, turn with tongs and cook for a further 20mins. Cover lamb loosely with foil and rest it for 10 minutes before serving.
While the lamb rests add the oil to a frypan and heat over a moderately-high heat. Add the capsicum, corn, garlic and cumin. Cook for 2-3mins, stirring occasionally. Remove from heat and stir in the coriander and mint. Serve the sliced lamb with the corn salsa.
TIPS
Ask your butcher to bone and butterfly the leg of lamb for you.
Sumac is the dried fruit of a shrub, native to the Mediterranean. It is sold coarsely or finely ground. Sumac has a lemony, citrus flavour with very little smell. You could use grated lemon rind to replace it.
Test for doneness with tongs. Rare is soft when pressed, medium is springy and well done is very firm.
