Heat oven to 275 ºF (140 ºC). Lightly spray 9x9-inch (22x22-cm) metal roasting pan with canola oil cooking spray and set aside.
Pat roast dry. Cover entire roast with ground black pepper and shake off excess. Place in prepared pan and roast in preheated oven for 1¼-1¾ hours or until internal temperature registers 140 ºF (60 ºC) with instant-read thermometer. Remove from oven and tent loosely with foil.
During last 30 minutes of cooking, prepare sauce. In medium saucepan, bring beef broth and water to a boil. Remove from heat and add mushrooms, covering them well with liquid. Let set at room temperature for 30 minutes to soften. Drain mushrooms, reserving broth. Coarsely chop mushrooms.
In large skillet, heat canola oil over medium-high heat. Add shallots and cook for 1-2 minutes or until soft; do not brown. Add garlic, peppercorns, Dijon mustard and reserved chopped mushrooms and cook for 1 minute. Deglaze pan with brandy and cook for 1 minute. Add flour and cook for 1 minute. Whisk in beef broth. Bring to a boil, then reduce heat and simmer for 8-10 minutes or until thickened.
Transfer meat to cutting board and slice thin. Cover with sauce and serve.