[ghaff]

There are a number of choices.

1.) You can treat it like pretty much any other engineering job and give a "normal" interview, which will vary a lot by company. You probably rely more on credentials than is sometimes the case with software development.

2.) You treat it more like writing, graphic design, video, photography, etc. and expect to see a portfolio. For fields like that, you might talk about thought processes or how they approach their work but the portfolio isn't really negotiable.

3.) In the case of software, you can maybe have someone effectively create a portfolio for the interview but now you're back to someone putting a lot of time into creating something--albeit possibly something reusable.