To make Chermoula:.
Mix onion, garlic, flat leaved parsley, coriander, cumin, saffron, harissa olive oil and lemon juice together and let stand for 1 hour.
Starting at the thicker end of the leg of lamb cut down and around bone, scrape away as much meat as possible.
Cut down into but not through the thickest part of the meat and open out flat.
Spread chermoula mixture into both sides of lamb and marinate for at least 2 hours.
Barbecue for about 3/4 hour turning frequently.
Cut in thick slices across the grain and serve.
Note. Harissa is a fiery condiment widely used in Morocco. The basic ingredients are red chillies cayenne olive oil and garlic. It should be thick with the consistency of light mayonnaise. Harissa is delicious served with poached eggs or sausages.
Cooking time does not include marinating time.