Tie Roast: Start with a 12 inch piece of kitchen twine, and tie the roast. Tie crosswise at 1 ½ inch intervals. To tie, wrap a piece of kitchen twine around the beef tenderloin, and fasten with double knots, repeating along the length of the roast. Fold the thin ends under the roast, and tie into place. Knots should be snug, but not tight. This will help give the whole roast an even thickness to promote even cooking, and prevent over-cooking the thinner end pieces.
Salt: Set roast on a plate or in a shallow dish, and sprinkle salt evenly over the roast. Cover with plastic wrap, and let stand at room temperature for 1 hour.
Preheat oven to 300 degrees, and position oven rack to the middle setting.
After the hour in salt, use a paper towel to pat the exterior of the roast dry. Sprinkle pepper and granulated garlic over the roast, and spread the unsalted butter evenly over the surface.
Roast on a Rack: Set beef tenderloin roast on a roasting rack or wire rack inside of a rimmed roasting pan or baking sheet. Do not skip the rack, this allows for even heating.
Roast in preheated oven for 40-70 minutes, depending on desired doneness. Flip half way through roast time. For internal temp of 125 degrees (medium rare) roast 40-55 minutes. For medium or 135 degrees, roast for 55-70 minutes, use an internal temperature probe, or quick read thermometer to monitor temp.
Meanwhile, make herb butter but combining all ingredients in a bowl, and setting aside.
When roast is nearly done roasting, heat the vegetable oil in a 12-inch skillet, over medium-high heat, until oil is hot and just smoking. Remove roast from oven when desired temperature is reached, and place in skillet, searing all sides until well browned. About 4-8 minutes each side.
Once seared, transfer the beef tenderloin roast from the skillet to a cutting board, and spoon 2 heaping tablespoons of the prepared herb butter over the top.
Rest the meat: While the butter melts into the meat on the cutting board, just let it sit there for 15 minutes. Do not touch it or slice too soon. You want to give the juices a chance to redistribute.
Carve: Cut the twine, and then carve the beef tenderloin into ½ inch thick slices, and serve with more herbed butter!