Best way is to paid-intern an engineer for a week/month and try them out (if they're willing) and see how they fit and might be able to expand on your current culture. That's really the only good way.
Asking questions in an interview, no matter how clever or insightful they may be, has been and will forever be a crap shoot.
Asking questions in an interview, no matter how clever or insightful they may be, has been and will forever be a crap shoot.