Does the alcohol in beer evaporate when you cook? Yes and no.

When alcohol mixes with water, it forms a compound called an azeotrope. When vapors rise off this liquid, they contain both alcohol and water. The Cook’s Illustrated Cookbook states that therefore, in dishes where a lid is used, more alcohol remains in the final dish: “Because most stews and braises are cooked in lidded pots, significant alcohol retention is the rule rather than the exception.”

So yes, some alcohol cooks off during preparation, but probably not all of it.