Preheat the oven to 180 degrees Celsius (356 degrees Fahrenheit) regular oven. The temperature, however, depends on your oven.
Start by trimming the beef tenderloin of fat and sinew. If you buy the meat from a butcher, you can ask him to do it.
Beef tenderloin is quite uneven in size, so you can either roast only the middle part (chateaubriand) to make it uniform or tie it up with kitchen string. If you buy the meat from a butcher, you can ask him to do it.
Season the meat with salt and pepper. If you want to give the meat a little extra flavor, you can season it with fresh thyme, rosemary, or garlic.
Brown the meat on a grill pan, regular pan, or in a roasting pot with butter and oil for 5-6 minutes. Give it a couple of minutes on each side.
Then place the tenderloin in the oven with a meat thermometer in the center of the meat. Roast it to an internal temperature of 56-60 degrees Celsius (133-140 degrees Fahrenheit). It takes 20-25 minutes, again depending on your oven.
Take the roast out. It does not need to rest, but if it does, it should not be wrapped as it will continue to cook.
Carve and serve! Feel free to add freshly ground pepper and sea salt flakes on top. Bon appétit.