We recently went through a hiring process using a recruiter. Our assumption was that the people they vetted were "legit" and we didn't need to do any additional work to verify that they had the skills they said they had. If the recruiter wastes our time it's a surefire way for them to never get business again.
Anyway, in lieu of a coding interview, I opened up a couple of tickets (one a long term change request, another a real life problem we encountered just the day before). I provided them logs and answered questions and watched the interviewees move through both scenarios.
We capped the time at an hour. The focus was more on the interaction between them and myself—it actually used the "real stuff" they'd encounter.
I was amazed at the diversity of the responses and how differently people approached a problem.