Forgetting fat cooks differently
One of the most frequent applications of the sous vide technique is certainly making steak. People adore the fact that a steak cooked in water maintains all of its juices when done properly. Instead of overpowering your steak with oil, heat, and salt, use sous vide to intensify its taste. You're left with a juicy, tender steak that's perfect for steak aficionados.
What possibly could go wrong with that? Because fat starts to render at a particular specific temperature, failing to render it or over-rendering it will make the meat tasteless. The underlying cause of your sous vide meat becoming rubbery is that fat, if not rendered correctly, will start to render at 130 F. Because you're cooking the steak slowly and thoroughly for maximum tenderness, it's simple for temperatures to fall short of reaching the necessary heat for the desired crispy edge. An easy fix is to sear your steak beforehand, which will start the fat rendering process before placing it in the sous vide bag.