Just a thought here, as Mike eluded to a bit, it might be good to step back to define what makes a "good" ID portfolio. Our field is pretty broad, and ever growing in scope. So what kinds of "good" are we looking for needs to be asked. Every candidate has his or her strengths, and when building a team it is good to get diverse designers on board to tackle problems from different perspectives. Here are just a few types of designers I have worked with:
Really good at the front end innovation process. More concerned with coming up with something totally new/distruptive. Often good with running workshops, brainstorms, always wants to get people to pull back and think about the larger context. Often good at defining problems. Might also be good at design research.
Loves working with those innovators. Typically great visualization skills, form giving. Good understanding of semantics. The ability to work with developers and engineers to start bringing things to life. Might partially be an innovator personality or a development personality. Might be great with "design" level CAD.
Loves solving the many design problems that pop up once an idea has been approved. Might have an ME background or more of an ME leaning. Typically loves to learn about manufacturing techniques. Usually great at communicating directly with factory and sourcing people. Might also be good at doing really tight, almost production level CAD. Loves finding the design opportunities on the product that the innovators and ideates missed.
This is your all rounder, jack of all trades, master of none. In my experience building teams this is usually the first hire. You need people who love the entire process and who's enthusiasm and willingness to help maybe eclipses ability in any one area.
As you could imagine, the portfolios for these archetypes might vary quite a bit. For innovators I would expect to see pictures from research trips, workshops, except. Innovation pipeline docs, concept sheets showing ideas and the evaluation metrics created to prioritize them. Where an ideates I'd expect to see hot sketches and CAD renders. For more development minded designers I'd expect to see spec sheets, red lines of factory blueprints, things like that.
Also, I made those categories up just to creat some generalizations for the sake of discussion. Don't take them too literally