1) Give you a complex customer scenario: “Customirage inc. would like to purchase products A, B and C, they would like the following features…They are interested in a geographic DR solution along with an A-A failover….they also have the following limitations…”
2) Then give the candidate about 10 minutes alone, and ask them to come up with the following when you come back:
1) The most complete architecture he can give.
2) A hand written architecture diagram.
3) What technologies did he rely on.
4) How will your company implement and support this solution.
3) Ask the candidate to present his solution as if you were the customer, while you ask the most distracting and challanging questions on the architecture, see how he deals with stress and how he handles explaining his ideas under pressure.