The tangerine technique is explained in the course. Basically it helps us to create a focal point at the back of the head. When we are working with a heightened sense of awareness we sometimes notice activity taking place at that point of our head. It also works in reverse... by throwing our attention there we trigger the activity. The tangerine is an image that helps us to focus without becoming overwhelmed with too much detail.
The how to use the technique is in the course.
Alex