Cut the rhubarb into 1 in / 2.5 cm lengths, rinse underneath cold running water, and put in a saucepan. Cover and simmer gently with the spice until the fruit is soft. Stir in sugar or honey to taste, remembering that the rhubarb will be further diluted by the cream or yoghurt. Cook a little longer until the sugar has dissolved. Allow the fruit to cool completely. Whip the cream, and gently fold it into the fruit pulp, or fold the fruit pulp into the yoghurt, if using it (fold the lighter texture into the heavier). Spoon into bowls or glasses and chill until required.