The term "tenderloin" can refer to two different cuts of meat: the whole tenderloin, a thick piece of muscle shaped somewhat like a fat fish, or a steak cut from the whole tenderloin. Cooking a whole beef tenderloin usually involves roasting or grilling it; because it would not even fit in most pans and because it is so thick, a whole tenderloin is not a good candidate for pan frying. Beef tenderloin steaks (which include fillet mignons, chateaubriands and fillet steaks), on the other hand, work well in a pan.
Remove the steaks from the refrigerator (if they are cold) and allow them to warm to room temperature. Pat the steaks dry with paper towels to remove any excess moisture.
Rub both sides of the beef tenderloin steak with olive oil, salt, pepper and any other seasonings you wish. You can use dried spices such as paprika or finely chopped fresh seasonings such as garlic or rosemary.
Heat the empty skillet on medium-high heat until it is very hot, about 5 to 10 minutes.
Place the beef tenderloin into the hot skillet and cook it for anywhere from 3-1/2 to 13 minutes depending on its thickness; steaks that are 1/2 inch thick will be done near the lower end of the time range, while those of 1 inch thick will take up to the full 13 minutes. Turn the steak several times during its cooking time. This will provide you with a medium-rare tenderloin steak; cook it for longer to achieve medium doneness. For best flavour and texture, do not cook your tenderloin steak beyond medium.
Remove your steak from the pan and allow it to rest on a plate for two to three minutes before eating or serving it.
Use a meat thermometer to check the inside temperature of your steak to determine its doneness. Shoot for 145F for medium-rare or 160F for medium.