Rib Roast with Roasted Garlic Thyme Sauce

7- to 8-pound trimmed prime beef rib roast* (sometimes called standing rib roast; 3 or 4 ribs)
1 TBS vegetable oil
2 heads garlic
3 TBS chopped fresh thyme leaves
1/4 cup minced shallot
2 TBS red-wine vinegar (use balsamic vinegar for more flavor)
1-1/2 cups dry red wine
1 bay leaf
4 cups beef broth (may want to reduce to 2 cups)
1-1/2 TBS unsalted butter, softened
1-1/2 TBS all-purpose flour if using beef broth

Preheat oven to 475°F

Put roast, ribs side down, in center of a 13x9" flameproof roasting pan and rub all over with 1/2 TBS oil.

Cut about 1/2" from tops of garlic heads to expose cloves and discard tops. Rub beef all over with cut sides of garlic and sprinkle with 2 TBS thyme, pressing to adhere. Season beef generously with salt and pepper.

Put garlic heads on a double layer of foil and drizzle with remaining 1/2 TBS oil. Wrap garlic tightly in foil.

Roast beef in middle of oven 30 minutes. Remove beef from oven and with a bulb baster skim all but about 1/2 cup fat from pan. Baste beef with fat remaining in pan.

Reduce temperature to 375°F.

Add garlic to oven. Roast beef, with garlic, 1-1/4 to 1-1/2 hours more, or until a meat thermometer inserted into center of meat registers 115°F. (Some recommend cooking to 120°F for medium rare) 130°F is hard to reach. I found use of digital thermometers and good wrapping does compensate for need of higher cooking. And if temps are not taken in the middle you may have an error reading. 115°F/120°F worked for me.

Transfer garlic in foil to a rack and transfer beef to a platter, reserving pan juices. Let beef stand 25 minutes. (Meat will continue to cook, reaching about 130°F for medium-rare.)

While beef is standing, remove all but about 2 TBS fat from pan. Add shallot to pan and on top of stove cook over moderate heat, stirring, 2 minutes. Unwrap garlic. Protecting your hand with a doubled paper towel, squeeze roasted garlic into shallot mixture and discard skins. Add vinegar, wine, bay leaf, and remaining TBS thyme and boil mixture, scraping up brown bits and mashing garlic with a wooden spatula against bottom of pan, until reduced to about 1/2 cup, about 5 minutes.

In a small bowl mash together butter and flour to make a beurre manié . Stir beef broth into garlic mixture and boil sauce until reduced to about 2 cups. Whisk beurre manié into broth mixture and cook over moderate heat, whisking, until sauce is smooth and slightly thickened, about 3 minutes. Pour sauce through a fine sieve into a bowl, pressing hard on solids. Season sauce with salt and pepper.

Cut rib roast into slices and serve with sauce.

Serves 8.