How to hire good designer?

I wouldn't actually rely on a portfolio. I would rely on what is the level of participation, who are actually interested in this kind of a career. At that point you are only gauging for that. They are way too young to have any meaningful body of work. Beyond the early career question, there are clearer signals. I try not to hire the world-saving person, the typical Batman-style designer who joins because they saw a problem they want to fix. That person will always put their need to fix problems above the journey. You should join a design team for the journey. The other things I look for: deep respect for engineering, because without that person your vision may not become reality. And some interest in art.