Season all sides of your New York strip.
Top with smashed garlic and fresh thyme sprigs.
Place inside a gallon size FoodSaver® Sous-vide Vacuum Seal Bag. Seal well.
Heat your sous-vide machine to the desired temperature, rare (120-128 °F), medium rare (129-134 °F), medium (135-144 °F), medium-well (145-155) or well done (156 °F).
Submerge vacuum-sealed bag in water. It should sink.
Cook for 45 minutes to 2 1/2 hours. You can cook it longer, but the chemical make-up of fibers starts to change and while it will remain cooked to temperature, the texture will change.
Carefully remove the bag from water bath, cut to open.
Heat large cast-iron pan over high heat to smoking point. It needs to be ridiculously hot. As hot as you can get it!
When hot, add butter and steak immediately after.
Cook for no more than 90 seconds, flipping from one side to the other every 15 seconds, finally giving the edges a quick sear.
Transfer to a cutting board, slice against the grain.
Top with Au Poivre Peppercorn Sauce and Maldon sea salt.