First mix the hot stock with the couscous in a bowl, then stir in the orange juice & zest. Preheat the oven to 190°C.
Finely chop and mix together the nuts, apricots & mint - it's best done in a food-processor.
When the couscous has absorbed all the liquid, add the chopped ingredients and stir well to create the stuffing.
Open up the lamb joint and season all over with the salt, pepper & cinnamon.
Spread the stuffing inside then close up again, securing with string.
Put into a roasting tin. Drizzle over the oil and cover loosely.
Cook for an hour - plus or minus 5 minutes for pink or well-done.