Yesterday, I was presented with a problem – how to cook in one sous-vide cooker steaks for people with different preferences, ranging from rare/medium-rare to medium-well-done. My solution, which seemed to work well, was to take advantage of the wide range of time which a steak can be in a sous-vide cooker (~45 minutes to 4 hours), and to add the steaks to the cooker in order from most cooked to least cooked while dropping the water temperature for each addition. Each of the steaks was in a separate ziplock baggie, and I told them apart by putting differing amounts of scallions in each bag. The fundamental idea is that the steaks cooked at the higher temperatures can stay warm in the cooker at the lower temperatures without any downside as long as the total time in the cooker stays within 4 hours.
T=0 Heat water to 135 degrees. When at temperature, add the steak which you want to be most well-down
T=1 hour. Reduce water temperature to 130 degrees. Add the steak you want done to medium
T=2 hours. Reduce water temperature to 125 degrees. Add the steak you want done to rare/medium-rare
T=3 hours. Heat barbeque grill as high as it can go. Remove steaks from the cooker. Pat steaks dry, and grill for 4 minutes, flipping each minute, until a nice crust forms. Serve immediately and enjoy.