Filet or Tenderloin is a unique cut; relatively lean but quite tender it requires very little cooking time and is best done only to “rare” to “medium- rare” (remove from heat at 115 to 130 deg F and rest beef 2-5 minutes before slicing). It has a delicate flavor and -with little fat- is intolerant of overcooking; so unless you are a grill master it’s best to bypass the grill in favor of the sautee pan.
This recipe from Aidells and Kelly (The Complete Meat Cookbook) for 1 to 1.5 pounds of steak involves a simple pan sauce to compliment the mild beef flavor. Simply ratio the sauce ingredient quantity to the weight of steak you are preparing so the reduced sauce flavor doesn’t overwhelm the steak. Reliable, high quality results that I’ve benefited from more than once.
Dry steak surface with paper towels and sprinkle both sides with salt, pepper and fresh (dry works in a pinch) rosemary.
Heat heavy skillet and add 2 T olive oil. Adjust heat to just below smoke point and add beef, sauteeing 3-5 minutes per side to an internal temp of 115 to 130 deg F. Remove to a pre-warmed plate, cover loosely and rest.
Sautee 2 t minced garlic in remaining oil in skillet until just turning color. Add 1/4 cup vermouth and reduce to a syrup consistency while stirring with a spatula. Add 1/4 cup beef or chix stock, 2 t soy sauce and 1 T balsamic vinegar. reduce to syrup while stirring . Remove from heat and stir -melt-in 1 T butter. Serve finished sauce over rested steaks on pre-warmed plates.