It's a fair point; hiring is hard.

It's been a while since I had to hire outside your "people you've worked with before" bucket, but when I did, here are the two questions which worked best:

1. Tell me about a time you analysed a complex problem and came up with a solution.

2. Tell me something creative you did at work. Something you're proud of.

In my experience, a good candidate typically had excellent answers to those questions, because (1) a good candidate has had to do some real engineering at some point and they can tell you about it, and (2) a good candidate has done technical work which they're really proud of just in and of itself, and they want to tell you about it.

A technical question was useful in reducing false positives, but something a couple of steps above FizzBuzz should be fine for that. You just find out anything useful about a candidate by asking them to recreate some esoteric CS algorithm on the spot, unless you really need to select for people who can recreate esoteric CS algorithms on the spot.