Ask the person to describe the last three tickets they worked on. Listen to them speak, and ask yourself if it is someone you could work with. At the end of the third description, if the answer isn’t obvious, you were the wrong person to conduct the interview.

That’s it. Seriously. One interview. No computers. Max 30 minutes. If you need more than that you have a decision-making disorder.

That's pretty bold. Not sure if I could grasp someone's technical skills just from that alone.