Larry Camejo wrote:
How do you teach a beginner to achieve this state and how do you test or check to ensure that it is in fact there (or not there)? When it is achieved how do you ensure that it is not lost again?
IMHO, you do not teach "beginners" no-thing-ness other than as a direction oriented concept.
That said, train slowly and relaxed, attempt to keep the mind as still/empty as possible, breathe, and enjoy yourself.
No-thing-ness refers more to the attachment to something, so slow randori teaches going from one "thing" to another without staying attached.
Read sport psychology "flow" or "peak performance" states.
You achieve it by what you don't do rather than what you do. If it lingers, stays attached to itself, you have already lost it.
Did that muddy the mind more?