Porcini-Crusted Beef Tenderloin With Truffle Butter Sauce

• 1 (6- to 6 1/2-pound) whole beef tenderloin, trimmed of fat, silverskin, and the chain (see Cooks' Notes); or a 5- to 5 1/2-pound well-trimmed tenderloin roast
• Salt
• Freshly ground black pepper
• 4 tablespoons olive oil, divided
• 1/2 ounce (about 1/2 cup) dried porcini mushrooms, ground to a powder in a blender
• 1/4 cup (2 ounces) black-truffle butter, softened
• 1/4 cup all-purpose flour
• 1 pound crimini (baby bella) mushrooms, trimmed and quartered into wedges
• 3 cups beef stock or low-sodium broth, divided
• 1/2 cup chopped scallion greens
• Kitchen string; large heavy roasting pan; instant-read thermometer

1. Make a deep cut into the top side of tenderloin, about 4 inches from tail end, to facilitate folding the tail end under the roast to give the meat a more uniform thickness. Tie roast at 1-inch intervals with kitchen string.
2. Heat oven to 350u0b0F with rack in middle.
3. Pat tenderloin dry and sprinkle all over with 1 teaspoon each salt and pepper, rubbing into meat.
4. Set roasting pan over 2 burners, then add 3 tablespoons oil and heat over medium-high heat until shimmering. Brown tenderloin on all sides, about 10 minutes.
5. Sprinkle porcini powder evenly on top of tenderloin and roast in oven until thermometer inserted diagonally 2 inches into center of thickest part of meat registers 120u0b0F, 30 to 40 minutes.
6. Toward end of roasting tenderloin, stir together truffle butter and flour. Heat remaining tablespoon oil in a 12-inch heavy skillet over medium-high heat until shimmering, and saute mushrooms with 1/4 teaspoon each salt and pepper until liquid released by the mushrooms evaporates and mushrooms are tender and golden, 10 to 12 minutes.
7. Add 2 cups stock to skillet and simmer, stirring up brown bits, 1 minute. Remove skillet from heat.
8. Transfer tenderloin to a cutting board and let stand 15 minutes (internal temperature will rise to about 130u0b0F for medium-rare).
9. Set roasting pan over 2 burners and add remaining 1 cup stock. Bring to a boil, scraping up brown bits, then pour stock into mushroom mixture in skillet.
10. Bring mushroom mixture to a boil and whisk in truffle butter mixture, bit by bit. Reduce heat and simmer, whisking occasionally until thickened, about 2 minutes. Stir in scallion greens and salt and pepper to taste.
11. Cut tenderloin into 1/2-inch-thick slices, discarding string, and serve with sauce.

beef tenderloin, salt, freshly ground black pepper, olive oil, porcini mushrooms, blacktruffle butter, allpurpose, crimini, beef stock, scallion greens, kitchen string

Taken from www.epicurious.com/recipes/food/views/porcini-crusted-beef-tenderloin-with-truffle-butter-sauce-387490 (may not work)