Try my best to test their systems programming knowledge and general programming expertise, NOT leetcode or academic memorization;

stuff like the pros and cons of JWT, when orchestration is necessary, APIs vs message queues, their opinion on statically vs dynamically typed languages, etc

these questions don't tell you directly how efficient they will be on a project or language stack, but they DO tell you whether or not the person actually understands programming at a deeper and wider level, and not just experts at regurgitating generic PRs for your average 10LOC ticket