Preheat your sous-vide machine to the desired temperature (see the doneness chart below).
Generously season both sides of the steak with salt and pepper. Place the steak in a heavy-duty 1-gallon resealable plastic bag. Drizzle the olive oil over the steak. Add the bay leaf to the bag.
Press out as much of the air as possible and seal the bag. Submerge the bag in the preheated water. Clip the top of the bag to the pot with a binder clip.
Cook the steak to the desired temperature. For a 1.5 inch – 2 inch steak, allow 2 hours for the steak to cook to 133F. (Once the steak has reached the desired temperature, it can sit in the bag in the water with the machine on for up to 1 hour before finishing, if desired.)
To finish the steak, heat the butter in a heavy-bottomed skillet over high heat. When the butter has stopped bubbling, add the steak from the bag, reserving the cooking juices to make the optional pan sauce).
Add the thyme, rosemary, and garlic. Swirl the steak in the pan for 1 to 2 minutes per side, until both sides have a well-browned crust.
For The Sauce
Remove the steak from the pan. Add the reserved cooking juices to the pan. Bring to a simmer. Add the butter. Whisk until the liquid reduces and thickens slightly. Remove the pan from the heat. Season to taste with salt and pepper.
Slice the steak or cut it into two pieces. Serve with the pan sauce, if desired.