Process garlic in food processor until finely chopped. Add oil, vinegar, peppercorns and Knorr® Chicken flavor Bouillon and pulse until paste forms.
Make several 2-inch long deep slits, about 2-inches apart, through skin and into meat of roast. Fill slits with garlic mixture, turn roast and repeat. Rub any leftover mixture on outside of roast. Cover and refrigerate at least 1 day or up to 3 days.
Preheat oven to 450°.
Place roast, skin side up in roasting pan. Roast 1 hour. Reduce oven temperature to 325° and roast an additional 2 hours or until meat thermometer inserted in thickest part reaches 150°. Let stand covered 10 minutes before slicing.