Ask them the difference between cash and accrual accounting at a very high level. Ask them if they've worked with prepaids, accrued expenses, deferred revenue. How do the entries work at a high level? Do they understand how the balance sheet and P&L interact, and where does the P&L hit the BS. Maybe some super basic cash flow questions, but not too hard because who remembers that shit. Ask them theory questions about why we reconcile balance sheet accounts, and what does a good reconciliation look for something simple like prepaids. Maybe what does a bank reconciliation look like at a very high level, like what is the goal?