Holly Taylor estimates she's interviewed hundreds of people in her decade-long career in the HR space.

The head of people at Public Digital, a London-based consultancy, says she tries to be innovative and equitable in the hiring process, such as recently sending interview questions to job candidates in advance.

But one question is her favorite to ask in interviews, even though "it stumped me so much" when she first heard it seven years ago: What is the most valuable piece of feedback that you have received in your career?

"The reason why I like that is because when they answer it, it gives you a really good understanding of how humble [or] vulnerable they're willing to go with their answer," Taylor tells CNBC Make It.

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Some people reflect on a constructive piece of feedback they got at a crucial point in their career, and how learning from the criticism ultimately propelled them forward.

They explain "this was the feedback, this is how I approached it, this is how I changed, and this is the impact of having that feedback," Taylor says.

Sometimes, people give an answer about how they work or interact with colleagues, whereas others discuss how they improved on a technical skill.

"When I was interviewing tech people, they'd say, 'I was writing part of this code incorrectly,'" Taylor says. "So it is really interesting to see where people go with it."

Asking this question isn't too different from inquiring about someone's greatest weakness or area of improvement. However, this framing prompts candidates to think about specific feedback they've gotten in terms of what their boss, team or organization needed them to improve on.

On the flipside, some candidates will focus on the positive and give an example of feedback they got about something they excel at.

Taylor says these responses can be equally insightful: "That's no right or wrong answer. You learn a lot from the person when they say that."

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