Here are the following ingredients:
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Follow these cooking methods/directions:
Pat roast dry with paper towel and pierce all over with a fork. Combine mustard, rosemary, salt and pepper in a small bowl. Brush all over roast.
Place roast on rack in shallow roasting pan. Insert oven-safe meat thermometer into centre of roast. Roast, uncovered, in preheated 275°F oven for about 4 hours for medium-rare (145°F/63°C for medium-rare, or 160°F/71°C for medium, or 170°F/77°C for well-done).
Rosemary Mushroom Sauce: Meanwhile, soak dried mushrooms in boiling water in a heatproof bowl for about 10 minutes or until softened. Drain, reserving soaking liquid. Chop soaked mushrooms; set aside.
Heat oil over medium-high heat in a large skillet; cook onion, stirring, for 3 minutes or until softened. Add fresh mushrooms, salt and pepper; cook, stirring, for about 8 minutes or until golden brown and liquid evaporates. Set aside.
Transfer roast to cutting board, cover with foil and let rest for 15 minutes.
Meanwhile, drain off fat from pan drippings. Add reserved mushroom soaking liquid, soaked dried mushrooms, rosemary and beef stock to pan drippings; bring to a boil over medium-high heat, stirring and scraping up brown bits stuck to pan. Gradually stir cold water into flour in a small bowl until smooth; gradually whisk into pan. Boil, whisking, for about 4 minutes or until thickened. Stir in cooked mushroom mixture and parsley. Heat through.
Carve roast across the grain into very thin slices and serve with piping hot mushrooms sauce.