Fill a stock pot or sous vide container 3/4 full of water. Place on heat-proof surface and add immersion circulator.
Heat water to temperature based on your preferred doneness for your steak. (126°F = rare, 129°F = medium-rare, 133°F = medium, 140°F = medium-well, 147°F = well done).
While water is heating, season steaks and put them in a single layer in a 1-gallon plastic zip-top bag. (For three steaks, I placed two steaks in one bag and one steak in another bag.) Add a drizzle of olive oil.
When water is heated, lower each bag into the water making sure the meat is fully submerged. Fold the top of the bag over the side of the stockpot. Clip bag to the side, if needed.
Set timer for cook time. Cook time depends on thickness of your steak (1/2-inch = 30 minutes, 1-inch = 60 minutes, 1 1/2-inches = 90 minutes).
After cook time is finished, remove bags from sous vide and remove steaks from the bag(s). Preheat heavy skillet over high heat. Place 1 tbsp butter or olive oil in skillet then sear steaks 1 minute on each side.