"Tell me about a time you had to mentor a senior engineer into becoming a stronger technical leader. What gap did you see, how did you approach it given they were already senior, and what changed as a result?"
This question tests whether you can develop talent without relying on formal authority, especially when the person is experienced and may not initially see the need to change. Interviewers want to understand how you diagnose leadership gaps, build trust, give difficult feedback, and create a practical development path rather than offering vague encouragement. They are also looking for judgment: mentoring a senior engineer requires respect, nuance, and clarity about business impact.
A strong answer uses one specific example with clear stakes: perhaps the engineer was strong technically but weak in delegation, stakeholder communication, decision-making, or mentoring others. The best responses show a thoughtful coaching approach, concrete actions over time, measurable improvement in team or project outcomes, and a lesson learned about how to influence peers or near-peers effectively.