When recruiting I tend to look for intelligence (looking at a problem from more than one angle) and engineering mindset (leverage critical thinking to solve the problem) over a skillset (Guru level Solidity developer).
I'd appreciate hearing what you guys think are good interview questions to mine a good engineer from a group of applicants.
It is obvious that you are looking for talent rather then knowledge. So don't ask them questions like the above, instead give them a problem to solve.
Just give them some small portion of work that you will want them to do or something related to it and see how they do.