Step 1

Season the steak liberally with salt and pepper. Place in a vacuum-seal bag with the thyme, garlic, rosemary and lemon and vacuum seal closed. Alternatively, place the ingredients in a sealable plastic bag and dip the bag into a large bowl of water to displace the air before sealing shut.

Step 2

Preheat a pot of water fitted with a sous-vide immersion circulator to 129° according to the manufacturer's directions. Cook the steak for 2 hours, making sure it is completely submerged in the water. Remove the bag from the pot and take the steak out of the bag, drying with paper towels.

Step 3

In a large cast-iron skillet, heat the vegetable oil over high heat. Add the steak and cook, flipping once until seared on both sides, about 1 minute per side. Add the butter and baste the steak for 10 to 15 seconds more. Transfer to a board to rest for 5 minutes.

Step 4

Slice the steak and garnish with flaky sea salt, then serve.