Preheat sous vide to your desired temperature (120°F/49°C for rare, 129°F/54°C for medium-rare, 135°F/57°C for medium, 145°F/63°C for medium-well, and 165°F/74°C for well-done).
Place steak(s) in vacuum seal bags along with butter, and herbs, and a little salt.
Once sous vide comes to temp, add sealed steaks and cook for 1 – 2 hours.
Remove cooked steaks from sous vide and from vacuum bags, then pat them completely dry to aid in searing. Dust all sides with salt and pepper.
Heat cast iron skillet to searing temperatures (400-450°F-/204-232°C), then add cooking oil.
Add steaks and sear on all sides until you have a nice brown crust.
Optional: Cool skillet, add butter and herbs, and baste steaks.
Allow steaks to rest for at least 10 minutes, then slice against the grain and serve.
