The idea that setting a dish on fire “burns off” the alcohol is a myth. In a USDA-funded study (widely cited by Idaho State University and medical organizations), researchers measured how much ethanol remained in foods prepared with different cooking methods and found flambéing retained roughly 70–75% of the starting alcohol.
Alcohol loss depends on time, temperature, surface area, and whether the dish is covered, not on whether there’s a brief flame. The same USDA-derived retention table shows that even long cooking doesn’t reach zero—after about 2.5 hours of simmering or baking, around 5% can still remain—so flambéing, which is brief, cannot eliminate it.