Sprinkle tenderloin evenly with salt and pepper. Stir together butter and next 3 ingredients, and rub mixture over tenderloin. Cover and chill 1 to 2 hours. Place in an aluminum foil-lined 15- x 10-inch jellyroll pan.
Bake tenderloin at 400° for 50 minutes or until a meat thermometer inserted into thickest portion registers 145° (medium-rare). Remove from oven, and let stand 15 minutes. Serve with Avocado Bearnaise Sauce.