First, you need to prepare a beef tenderloin. For 45 minutes before cooking, the steak should be promaknut paper towels, add salt and pepper and leave to marinate for 45 minutes. Importantly, steak should be at room temperature.
Prepare a cast-iron pan and place it over high heat. Steak again wet paper towels to remove excess salt and spices.
In a frying pan pour the vegetable oil, put the steak and cook for 2 minutes on high heat. Then turn to the other side and cook another 2 minutes. Then gently turn the steak every 2 minutes, until its internal temperature will be 98 ° C (it takes about 8 minutes).
After 8 minutes in the pan, add the butter and when the butter is melted, thyme sprigs. Meat should be watered it with melted butter on both sides, remove from the pan, put on a platter and let it rest for about 10 minutes.
The finished dish can sprinkle with black pepper, cut and serve.