I found two good ways to ask for feedback about a job interview:

  • If you got the interview in part through a common connection — a friend of a friend or colleague of a friend or friend of a colleague — ask the non-threatening question via that connection.
  • In the future, ask that question DURING THE INTERVIEW:  “Let’s discuss what things may make you think I’m not an ideal fit for this role” – demonstrate in real-time that you can hear and respond to feedback.

Source: Nathan Wolfson’s answer to Quora question, “What is the best way to ask for feedback if you don’t get a job?