Tilt the bowl and drain away excess water. Set aside for 5 minutes. Line the couscousiere with a dampened napkin or cheesecloth and add the grain. Cover and steam 15 minutes. While the grain is cooking, prepare the flavoring.
Half fill a saucepan with water and add the pistachios.
Pour the pistachios onto a towel, fold the towel over them and rub to loosen skins. Separate pistachios from skins, going over them carefully. Combine the freshly blanched pistachios, extract and cinnamon in a food processor bowl and process for 2-3 minutes, until very finely ground and starting to become pasty. Reserve pistachio paste. After the couscous has steamed 15 minutes, remove it from the couscousiere in the cheesecloth and put it in a large, non-reactive roasting pan.