Method:

Pour half lemon juice over sliced avocados.  Peel oranges, removing outside membrane, and cut between membranes to remove skinless segments.  Combine prawns, oranges, celery and chives.  Line a large bowl with lettuce leaves.  Place prawn mixture in the centre and arrange avocado slices and pecan halves over it.  At the table, pour a little of your favourite dressing over salad and toss lightly to combine.