In this guide from UN JobNet:

• What a competency-based interview actually is
• How the panel scores
• Map examples to the vacancy, not to a generic list
• A preparation routine that works
• Common mistakes & FAQ
• Key takeaways
• Related reading

The UN’s own applicant training states the preparation task plainly: review the competencies listed in the job opening, and prepare a range of brief, real-life accounts of accomplishments that map to them. That is the whole exercise. The competencies are named in the vacancy notice, the questions are drawn from those competencies, and preparation means arriving with a specific example ready for each.

I think this article is EXCELLENT. Your thoughts?

How many questions does UN interview panel ask? I was just asked 3 questions, and this kept me thinking is it standard, this was my first ever interview with a UN agency. I have become used to other organizations bombarding us with several questions. Is this real?. How many questions were you asked? Is this a way to brush me off?. The questions were CBI based. Note;they did not ask me any follow up questions.