Make the simple Kasbah couscous side dish while the roast beef is cooking for your Moroccan-inspired meal. Our time-test results are based on a roast that was about 7¼-in (18 cm) long x 5½-in (14 cm) wide x 3¼-in (8 cm) deep. NOTE: ‘Time-to-cook’ figures are rough guidelines only as cook time is dependent on so many factors such as oven and thermometer accuracy, starting temperature of roast, roast shape and cut. A good thermometer is one of your best kitchen investments.