Red Wine Gravy For Beef

RED WINE STOCK: 2. Saute onion in oil and butter till lightly brown. 3. Add tomato paste, cooking till it turns dark. 4. Add garlic and cook for 30 seconds. 5. Deglaze with wine, scraping up brown bits off bottom of pan. 6. Add broth and thyme. Simmer till liquid reduces to about half, about 10 minutes. 7. Strain stock and save red wine stock SAUCE: 9. Heat butter and oil in saute pan over medium-high heat. 10. Saute mushrooms till barely done and still somewhat white in color. (Don't crowd, or they'll just steam.) Remove from pan and set aside. 11. Make a roux in the same pan by melting the butter and then whisking in the flour. 12. Cook over low heat till roux browns slightly. 13. Add wine stock, mustard, mushrooms. Simmer till sauce thickens. 14. Stir in sour cream or sprinkle blue cheese over already sauced tenderloin. (Both optional.)