Last week, LinkedIn announced to the world that I've been in the recruiting industry for 36 years. During that time, I've written a number of books about talent challenges and opportunities, but one thing continues to surprise me: More than 90 percent of hiring managers think they're good interviewers, yet rarely do they reach unanimous hiring decisions with other 90 percenters in the same room evaluating the same candidate.

This realization led me on a quest to find the one interview question that would yield universal agreement from hiring managers. It took 10 years of trial and error, but I eventually found it. Here's it is:

What single project or task would you consider your most significant accomplishment in your career to date?

To see why this simple question is so powerful, imagine you're the candidate and I've just asked you this question. What accomplishment would you select?

Then imagine that over the course of the next 15-20 minutes I asked you the following follow-up questions. How would you respond?

Can you give me a detailed overview of the accomplishment?

Tell me about the company, your title, your position, your role, and the team involved.

What were the actual results achieved?

When did it take place and how long did the project take?

Why were you chosen?

What were the 3-4 biggest challenges you faced and how did you deal with them?

Where did you go the extra mile or take the initiative?

Walk me through the plan, how you managed it, and its measured success.

Describe the environment and resources.

Explain your manager's style and whether you liked it.

What were the technical skills needed to accomplish the objective and how were they used?

What were some of the biggest mistakes you made?

What aspects of the project did you truly enjoy?

What aspects did you not especially care about and how did you handle them?

Give examples of how you managed and influenced others.

How did you change and grow as a person?

What you would do differently if you could do it again?

What type of formal recognition did your receive?

With an accomplishment big enough, and answers detailed enough to fill 20 minutes, this one line of questioning can tell an interviewer everything he or she needs to know about a candidate. The insight gained is remarkable. But the real secret ingredient is not the question; that's just a setup. The most important elements are the details underlying the accomplishment. This is what real interviewing is about -- delving into the details.