Mustardy Beef Tenderloin on Greens

From a magazine but not sure which one! The magazine states: "This elegant roast with its mustard coating deserves a mixture of full-flavored salad greens. Toss them with fresh tarragon leaves, the herb with aniselike overtones".

• Ready In: 1 hr 30 mins
• Serves: 6-8

Ingredients

• 3  tablespoons Dijon mustard
• 2  teaspoons olive oil
• 2  teaspoons black peppercorns, cracked
• 2  teaspoons fresh tarragon or 1⁄2 teaspoon dried tarragon
• 1  teaspoon kosher salt
• 1 (2 -3 lb)  beef tenderloin
• 1⁄4 cup  balsamic vinegar
• 8  cups  mixed baby greens
• 1⁄4 cup  fresh tarragon leaves

Directions

1. In small bowl stir together 1 tablespoons of the mustard, the olive oil, peppercorns, the 2 teaspoons fresh tarragon and the salt.
2. Spread mixture over the top and sides of the meat. Let stand for 15 minutes at room temperature or refrigerate up to 4 hours.
3. Preheat oven to 425 degrees and place meat on a rack of a shallow roasting pan.
4. Roast, uncovered, for 30-45 minutes or until meat thermometer registers 140 degrees for medium-rare.
5. Remove meat from pan; cover with foil and let stand 15 minutes before slicing.
6. While meat is standing, place roasting pan over low heat on the stove.
7. Add vinegar to the pan. Cook, scraping up the browned bits from the bottom of the pan. Stir in remaining 2 tablespoons of mustard and juices that have accumulated from standing roast.
8. If mixture seems thick, use water to thin to drizzling consistency.
9. Toss together greens and remaining tarragon leaves. Line a platter with greens mixture.
10. Drizzle greens with 3/4 the pan juices. Slice the meat; overlap the slices and now drizzle with the remaining pan juices.