1. Cut tenderloin into thin slices; set aside.
2. In a large sauté pan, heat 1 tbsp. oil over medium-high heat, swirling to coat pan.
3. Increase heat to high. Add mushrooms; cook until lightly browned (about 4 min.). Transfer cooked mushrooms to a medium bowl; set aside.
4. Return sauté pan to high heat; add remaining oil, swirling to coat pan.
5. Arrange tenderloin in a single layer in bottom of pan; cook until browned on first side (2 min.). Flip; continue cooking until browned on second side (about 1 min.).
6. Season tenderloin with salt and pepper; transfer to the bowl with the mushrooms and set aside.
7. Add demi-glace to the sauté pan, scraping up browned bits from bottom of pan; simmer until broth is reduced by ½ (about 4 min.).
8. Transfer demi-glace mixture to the bowl with the mushrooms and beef, scraping pan clean with a rubber spatula; set aside.
9. Return sauté pan to medium-low heat. Add butter; heat until melted.
10. Stir in shallots, brown sugar and tomato paste; cook, stirring frequently, until shallots are softened (about 2 min.).
11. Stir in flour; gradually whisk in wine.
12. Increase heat to medium-high; bring sauce to a boil, whisking constantly.
13. Reduce heat to medium-low; simmer until sauce is thickened (about 2 min.).
14. Adjust seasoning to taste; whisk liquid from mushrooms and beef into sauce.
15. In a small mixing bowl, stir ½ cup sauce from the pan with sour cream; stir sour cream mixture back into sauce.
16. Add mushrooms and beef to the pan; heat through. Adjust seasoning to taste; keep warm while pasta cooks.
17. Cook pasta according to pkg. directions; drain.
18. Divide pasta among 4 dinner plates; spoon stroganoff over pasta.
19. Garnish with parsley; serve immediately.

Switch-Up:

• Try a whole-wheat or bean-flour pasta to gain extra fiber, B vitamins and minerals.