Braised Beef Pot Roast with Mixed Peppercorns

1. Crush  1 tbsp (15 mL) of the peppercorns using rolling pin or mortar and pestle; combine with mustard and 1/2 tsp (2 mL) salt. Pat beef dry; rub mustard mixture all over roast. In large deep Dutch oven, heat 2 tbsp (30 mL) of the oil over medium-high heat; brown beef all over, turning with tongs, for about 10 minutes. Remove and set aside. Reduce heat to medium. Add remaining oil to pan if necessary; cook pearl onions and remaining salt, stirring, for 4 minutes or until golden. Using slotted spoon, remove onions and set aside.
2. Add  beef stock, red wine and remaining whole peppercorns; bring to boil, stirring and scraping up brown bits from bottom of pan. Return meat and any juices to pan. Cover and simmer over medium-low heat or in 325°F (160°C) oven, turning beef occasionally, for about 2 hours. Add pearl onions; cook until pearl onions and roast are fork-tender, about 1 hour.
3. Transfer roast to cutting board; tent with foil and let stand for 15 minutes before carving thinly across the grain. Skim fat from sauce and bring to boil over high heat; boil for about 12 minutes or until reduced to about 3 cups (750 mL). Serve with roast.