Self-inquiry is very simple. It is the simplest, humblest thing possible.

How

Do not think, or look for steps or a "how", or see it as a complicated process or practice through time, or a sophisticated philosophy.

Self

It is simply pointing to the fact that the end of the road is know who, or rather what you are. The seeker is the sought. That that is looking is what you are looking for.
What in the East is called the Self, the true or absolute self – the nameless silence with no opposite; Reality, Peace/Happiness. Satcitananda.

Inquiry

It is an Inquiry because if you knew the answer you wouldn't be asking the question. So, you don't come with an agenda (e.g., wanting something as a person, such as recruits, or proving something about your guru or yourself, or showing something, defending something, controlling, getting approval…). There is sincerity. Like a child.

Also points to the fact that answers are not pre-fabricated or given rigidly, (or nameable – it is the formless itSelf) like they are in religions, New Age beliefs systems and practices, self-help, psychology, etc... rather it is truly a living answer, an undivided whole, creative, real, intelligent, alive, spontaneous, open, new, now.

One can see why there's an apparent contradiction (what we call a paradox) to the mind:
The answer is always the same, yet different (time: always fresh and new for you; space: different ways of formulating it from different "teachers" and "students").

Thus in time, it is a on-going in the sense that is is a Living Question, as long as there are residues and life to be lived, and new expressions to be sung, celebrated, shared.
And in space, there are many "flowers in the meadow" (as Francis has said) so to speak.

One travels a great ways to come back home.

The answer is in you.

[Opening Eternity Now at random – this is regards questioning versus surrender:]

The truth is not a concept. … A real teacher will always welcome your questions, at least until you have a first hand knowledge of your true nature. Then, he may choose to answer your questions if he feels it appropriate to do so. For instance, he may help you expand your understanding of the spiritual perspective to a practical problem in your life, or he may simply remind you, here and now, of the truth you have already experienced. In both cases your question will find its answer in you. – Francis Lucille (p.107)

(5) Jesus said, Recognize what is in your sight, and that which is hidden from you will become plain to you . For there is nothing hidden which will not become manifest. –The Gospel of Thomas