Beef Tenderloin with Tarragon Mushroom Sauce

Trim beef of any visible fat; place in roasting pan. Stir mustard with pepper then spread over beef. Let stand at room temperature for 1 hour.

Preheat oven to 425 °F (220 °C). Roast beef for 10 min; reduce heat to 350 °F (180 °C) and roast for 25 min for medium-rare or 30 to 35 min for well-done. Remove from oven; let stand for 10 min before slicing thinly.

Tarragon Mushroom Sauce
In nonstick skillet, heat butter over high heat; sauté mushrooms, stirring often, for about 8 min or until lightly browned. Sprinkle with flour; cook for 1 min. Add onions; cook, stirring, for 1 min. Add broth and tarragon; bring to boil. Boil, stirring often, until liquid is reduced by half.

Stir in whipping cream and bring to boil. Reduce heat to medium-high; boil, stirring, for 2 to 3 min or until thickened slightly and sauce is reduced to about 1 cup (250 mL). Spoon sauce over servings of beef.

For the Adventurous: Soak 1/3 cup (80 ml) chopped dried porcini mushrooms in 1/2 cup (125 ml) hot water for 15 min or until softened; add mushrooms and soaking liquid to sauce along with broth; boil until liquid is reduced to about 1/2 cup (125 mL). Continue with step 4 above.

Make-Ahead Tip: Cover and refrigerate mushroom sauce for up to 1 day. Reheat before serving.