heat oven to 350 degrees. combine garlic, salt, pepper and rosemary; press into surface of beef roast. place roast on rack in shallow roasting pan. insert meat thermometer until bulb is centered in thickest part. do not add water or cover. roast 2 1/4 to 2 1/2 hours for medium rare to medium. remove roast when meat thermometer registers 140 degrees for medium rare, 155 degrees for medium. let roast stand 20 minutes. temperature will continue to rise about 5 degrees; 145 degrees for medium rare, 160 degrees for medium.
add potatoes after first 1 1/2 of cooking.
for sauce: in small saucepan, combine sauce ingredients. cook over medium heat 5 minutes or until bubbly, stirring occasionally.
carve roast into slices; serve with potatoes and sauce. makes 8-10 servings.