You can ensure your Brussels sprouts go down a treat this Christmas with Mary Berry's foolproof recipe , as she claims one 'essential' ingredient will make them delicious. Brussels sprouts are always a divisive part of the Christmas dinner , as some people love the tiny green balls and others think they're the worst vegetable in the world . But according to Dame Mary Berry , there's an easy way to make your Brussels an instant winner this year - by using just one 'essential' ingredient that