Can I audit my own restaurant?

The first pass, absolutely — that is exactly what the free diagnostics on this page are for. You need your monthly revenue, your purchase and payroll totals, your rent and your aggregator statements. Where a self-audit stops being enough: when the lines disagree with the bank balance, when multiple outlets blur the picture, or when the team has normalised the numbers for so long nobody questions them.

From Restaurant Profitability Audit: The Four Lines That Decide Your Margin — the full reading, with the method behind this answer.