43/4" to 1" thicktenderloin steaksabout 4-6 ounces each
Fill a large pot with warm water, clip or stand your sous-vide machine up in it according to the device’s specifications, and set the desired time to 40 minutes and temperature to 130 degrees fahrenheit for medium rare, 135 for medium, 150 for medium well and 156 or above for well done.
Season steaks liberally with salt, pepper and garlic powder. Place each steak in a FoodSaver® vacuum bag leaving at least 4 inches of space between the steak and the top of bag. Evenly distribute sliced garlic and rosemary sprigs between each steak and place on top between the steak and the vacuum bag.
Using two hands, slowly insert open end of bag, curl down, into the vacuum channel. Continue to hold bag until vacuum pump starts. When the vacuum progress lights illuminate let go of vacuum bag. When red indicator light turns off, remove the bag. Wait at least 20 seconds before sealing again.
Allow the water bath to come to temperature before adding your steak. Drop the bag into the water bath, making sure not to block the intake or output sections of your precision cooker. If properly sealed, the steak should sink. To further ensure the bag doesn’t block the sous vide cooker secure with a clip to the opposite side.
Once the time is up, remove bag from water and let rest up to 10 minutes if desired. Remove steaks from the bag reserving any juices and place steak on a paper towel–lined plate. Pat it dry very carefully on both sides. Season again with salt and pepper.
Heat the oil in a medium cast iron skillet over high heat. When the oil is shimmering, add the steak and sear until well-browned, about 30 seconds per side. Transfer steak to a cutting board and let rest for 5 minutes. Remove, top with a dollop of butter and serve.
Alternately, make an easy garlic rosemary pan sauce with the juices left in the bag and the little bits left in the pan after searing. Reduce pan to medium, add 2 tablespoons butter, minced garlic and chopped thyme. Add juices from bag and simmer until reduced, or add a splash of beef or vegetable stock if there aren't enough juices leftover. Remove from pan, swirl in a dollop of butter and serve alongside sous-vide steak.
If substituting a thicker steak cut like Ribeye, porterhouse, strip steak or any other cut add 20-30 minutes or more depending on thickness.Sealed sous-vide steaks can be pre-cooked and refrigerated up to 4 days or frozen up to 4 months. Reheat with sous-vide machine at 100 degrees Fahrenheit until warmed through, about 1 hour, before serving.