Peel pear, halve it lengthways and remove the seeds with a melon baller. Use a small, sharp knife to neatly remove the hard core leading to the stem.
Put the pear, cut side down, in a small saucepan with the orange juice, cover and bring to simmering point then cook gently for 8-10 minutes, just until tender, turning the halves over after 5 mins and spooning some of the juice over them.
Leave to cool in the juice. Peel the mandarin, divide into segments and remove the membrane covering each segment.
Put pear half in each bowl and spoon pan juices over. arrange mandarin segments around and decorate with a mint sprig.