Medium-rare sous vide steak - achieving coloring without slicing?
My observation for cooking steak sous-vide and avoiding this issue is as follows:


If I cook it in a complete vacuum, it really stays gray for a longer time. Cooking in a zip-loc bag helps me shorten the time the steak turns red.
Normally you’re not supposed to rest the steak after sous-vide cooking. However, resting can also help (without cutting into it) the steak turning red from gray.