Combine peppercorns and next 5 ingredients. Place roast, bone side down, on a rack in a shallow roasting pan. Spread peppercorn mixture over roast.
Bake at 325° for 2 1/2 to 3 hours or until a meat thermometer inserted into roast registers 140° or until desired degree of doneness.* Remove from pan and let stand for 15 to 20 minutes before slicing.**
Strain pan juices from roasting pan into a measuring cup. Skim off any fat drippings from top of juices, and reserve drippings for Yorkshire Pudding. Return pan juices to roasting pan; set pan over 2 burners. Add wine and broth to pan, scraping up any browned bits from bottom of pan, and boil 5 minutes or until mixture is reduced to 1 cup.
Stir together water and cornstarch; add to broth mixture, stirring constantly, 1 minute or until mixture boils and thickens. Remove from heat and serve with roast. Garnish, if desired.
*Note: Large cuts of meat will continue to cook from residual heat. Final temperature will rise 5° to 10°.
**Allowing meat to rest before carving brings juices back to the center, holding in flavor.