How to answer "What is your plan for this job?" during an interview?

I have been asked, twice recently, to prepare a presentation on how I would achieve the objectives of the job for the interview (first one) or to prepare a document on what my vision is for the role or the unit. I have approched this (unsuccessfully) as a test of how I would think through the issue and go about determining right actions vs actually presenting a plan as to what I would do.  Is there a recommended approach to answer this application/interview question?