OK, if you get the admittedly much tougher follow-up question as to why you were let go (and the truth isn't exactly pretty), your best bet is to be honest (the job-seeking world is small, after all). But it doesn't have to be a deal-breaker. Share how you’ve grown and how you approach your job and life now as a result. If you can position the learning experience as an advantage for this next job, even better. Keep your response short and focused. You want your answer to be brief. Select one or two specific qualities from the list you created to emphasize in your “sales pitch.” If you aren’t sure how to decide which to include, take another look at the job description and use your analytical skills to determine which qualifications would add the greatest business value.
Any candidate can read and regurgitate the company’s “About” page. So, when interviewers ask this, they aren't necessarily trying to gauge whether you understand the mission—they want to know whether you care about it. Start with one line that shows you understand the company's goals, using a couple key words and phrases from the website, but then go on to make it personal. Say, “I’m personally drawn to this mission because…” or “I really believe in this approach because…” and share a personal example or two.