*If you want to get ahead, you can cook this dish up to the end of step 3 the day before, then let it cool and keep it in a covered bowl in the fridge. When you are ready to serve, reheat the lamb while the couscous is soaking in step 4, making sure it is piping hot and bubbling.
*For a more peppery flavour, instead of coriander toss chopped rocket or watercress with the couscous.