Season the meat with salt and pepper.

Vacuum-seal the meat and cook it in a sous vide/water bath at 54 degrees Celsius (129 degrees Fahrenheit) for 2 hours.

Remove the meat from the bag and pat it dry, either with a dish towel or paper towel.

Heat a pan over high heat and add the oil. 

Add the meat and butter at the same time and sear for about 20-30 seconds on each side.

Remove the meat from the pan and slice the roast into thin pieces. 

When serving, add freshly ground black pepper and a good quality flaky salt to the meat.