Remove roast when meat thermometer registers 135°F for medium rare; 150°F for medium. Transfer roast to carving board; tent loosely with aluminum foil. Let stand 15 to 20 minutes. (Temperature will continue to rise about 10°F to reach 145°F for medium rare; 160°F for medium.)

Prepare Red Wine Pan Sauce. Skim fat from pan drippings, reserving 1 tablespoon. Heat reserved 1 tablespoon fat in 3-quart saucepan over medium heat until hot. Add onion; cook and stir 1 to 2 minutes or until tender. Place roasting pan over medium heat; add wine. Cook and stir 1 to 2 minutes or until browned bits attached to pan are dissolved. Add wine mixture and broth to onion in saucepan; bring to a boil over medium-high heat. Cook 12 to 13 minutes or until reduced by about 1/3 (about 1-1/3 cups). Reduce heat to low. Combine butter and flour in small bowl until smooth. Whisk into wine sauce; cook and stir 1 minute or until sauce is thickened.

Carve roast into slices; season with salt, as desired. Serve with wine sauce.

To Carve a Beef Rib Roast
Place roast on its large end on cutting board. Insert fork from the side, below the top rib. Carve across the "face" of the roast toward the rib bone.

Cutting from Bone
Cut along the rib bone with tip of knife to release slice of beef. Slide knife under beef slice; steady it from above with the fork and lift slice onto serving plate.