Finely chop dried mushrooms; soak half in 1/4 cup warm water. Set aside. Combine remaining mushrooms, oil, mustard, rosemary, garlic, pepper and salt; rub all over roast. Insert meat thermometer lengthwise into centre of roast so shaft is not visible. Place on rack in ovenproof skillet or shallow pan. Add 1/4 inch (5 mm) water to pan (to prevent dried mushrooms from scorching).

Cook roast, uncovered, in 450F (230C) oven for 10 minutes. Reduce heat to 275F (140C); roast until thermometer reads 145F (63C) for medium-rare, about 2 hours. Transfer roast to cutting board; tent with foil for 15 minutes, reserving pan drippings.

Slice roast and serve with Mighty Mushroom Sauce.

Mighty Mushroom Sauce

Heat reserved pan drippings in roasting pan on stove top over medium-high heat; add butter and melt. Add sliced mushrooms and chopped onion; saute until tender. Stir in reserved soaked mushrooms, soaking liquid and red wine and simmer 2 to 3 minutes. Stir in beef broth; cook, stirring until boiling. Stir in the cornstarch and water mixture; cook and stir until thickened. Season to taste. Makes about 1 cup (250 mL).