Porcini-Dusted Beef Tenderloin with Onion Jus

Beurre Manier: In small bowl, mash butter with flour until smooth; refrigerate for 15 minutes. (Make-ahead: Refrigerate for up to 24 hours.)

Meanwhile, in spice grinder or using mortar and pestle, grind porcini mushrooms until finely powdered. In large shallow dish, stir together ground mushrooms and all but a pinch each of the salt and pepper. Press all over tenderloin to adhere.

In large skillet, heat half each of the oil and butter over medium-high heat; brown tenderloin all over. Transfer to rack in roasting pan. Roast in 425°F (220°C) oven for about 35 minutes or until rare and meat thermometer inserted in centre reaches 140°F (60°C). Tent with foil and let stand for 10 minutes before carving into 1/2-inch (1 cm) thick slices.

Meanwhile, peel and halve shallots lengthwise, keeping root end intact.

Heat remaining oil and butter in same skillet over medium-high heat; saute shallots, white mushrooms and remaining salt and pepper until golden, 5 minutes.

Add Port, stock, vinegar and mustard; bring to boil. Reduce heat and simmer until shallots are tender, 15 to 17 minutes. Whisk in beurre manier until smooth and thickened. (Make-ahead: Let cool; refrigerate in airtight container for up to 2 days.) Serve with beef.

Source : Canadian Living Magazine: December 2007