Filet mignon is naturally tender but very lean, so traditional high-heat cooking can jump from perfect to overdone in a minute. Sous vide locks in your target doneness from edge to edge, then you add flavor with a fast, high-heat sear and a rich finishing sauce. Use lower temperatures for a silky, custardy center, and nudge higher for a more traditional steakhouse bite. This guide focuses on choosing the doneness window and the hold time that keeps filet buttery—not mushy.