Trim any excess fat from meat and discard.
Cut through tenderloin lengthwise to within 1/2-inch of the other side.
Lay meat open like a book. Spread meat with mustard. Lay basil and sage leaves on mustard.
Sprinkle with thyme leaves, garlic and pepper. Bring cut sides together and tie roast with cotton string at about 1-inch intervals to secure.
Coat surface of beef with butter and sprinkle with more pepper.
Lay roast, cut to the side, on a rack in a 12x17-inch pan.
Bake at 425° F until a thermometer inserted in center of thickest part registers 130 to 135° F for rare, 40 to 50 minutes.
Let rest in a warm place up to 20 minutes.
Transfer meat to a platter. Remove strings. Garnish with herb springs. Slice and add salt and pepper to taste.Servings: 4