For the poussins, preheat the oven to 400 degrees F (200 degrees C).
Place the poussins in a roasting tin. Pour the oil slowly over the top of the top of the poussins. Rub the oil into the poussins so that they are well coated.
Place the salt, sugar, cinnamon and paprika in a small clean bowl and mix well. Sprinkle the spice mixture over the poussins. Slice the lemon into quarters and then slice each quarter into 4 so you have 16 small pieces. Place the pieces around and in between the poussins.
Separate the garlic bulb into cloves and place the pieces around and in between the poussins. Transfer the poussins to the oven and cook for 1 hour to 1 hour 15 minutes, or until completely cooked through. Remove the poussins from the oven and then let them rest for 10 minutes in their tin.
Place the couscous, sultanas, spices and salt into a microwave-proof bowl and mix well. Add the freshly boiled water to the bowl and then cover the bowl with cling film. Leave the mixture to sit for 10 to 15 minutes, or until the water has been absorbed by the couscous. Remove the cling film from the bowl and stir the couscous with a fork to separate the grains. Carefully pour some of the juices that have collected in the roasting tin of poussins into the bowl. Stir the mixture again and season, to taste, with salt and freshly ground black pepper. Transfer the couscous to a serving dish.
Slice the pomegranate in half and extract a good quarter of the seeds. Place them onto the couscous. Sprinkle the chopped cilantro (coriander) over the top.
To serve, place the poussins onto clean plates and place the couscous alongside. Use the oven-charred lemon pieces and garlic cloves from the roasting tin to garnish.
Recipe courtesy of Nigella Lawson from Nigella's Christmas Kitchen, 2007