Step 1

Preheat oven to 225°F.

Step 2

Season tenderloin roast with 2-teaspoons salt and 1-teaspoon pepper. In a small mixing bowl stir together butter and miso. Coat roast with half the miso butter.

Step 3

Combine shallots and mushrooms in the bottom of roasting pan. Stir in remaining salt and olive oil. Form an elongated mound with the vegetables running lengthwise down the center of the pan. Place the rack in the pan with the tenderloin directly over the shallots and mushrooms.

Step 4

Slow roast 1 hour and 30 minutes (or until internal temperature reaches 105°F). Remove roast from oven, tent with foil and preheat oven to 500°F.

Step 5

Coat roast with remaining miso butter and return to the oven.

Step 6

Roast 10-15 minutes or until it reaches 125°F for medium rare. Tent with foil and allow to rest for at least 15 minutes. Slice tenderloin roast and serve with roasted shallots and mushrooms.