Ingredients
2 tablespoons butter1/2 pound sliced baby portobello mushrooms1 tablespoon Worcestershire sauce3 tablespoons horseradish mustard or spicy brown mustard1 tablespoon coarsely ground pepper1 tablespoon olive oil1 teaspoon salt1 beef tenderloin roast (4 pounds)3/4 cup crumbled blue cheese, divided1-1/2 cups french-fried onionsAdditional french-fried onions, optional
Preparation
Preheat oven to 425°. In a small skillet, heat butter over medium-high heat. Add mushrooms and Worcestershire sauce; cook and stir until mushrooms are tender, 6-8 minutes. In a small bowl, mix mustard, pepper, oil and salt.
Cut lengthwise through the center of roast to within 1/2 in. of bottom. Open roast and cut lengthwise through the center of each half to within 1/2 in. of bottom. Open roast flat; cover with plastic wrap. Pound with a meat mallet to 3/4-in. thickness.
Remove plastic. Spread mushrooms down center of roast to within 1/2 in. of ends; top with 1/2 cup cheese and onions. Starting at a long side, roll up jelly-roll style; tie at 1-1/2-in. intervals with kitchen string. Secure ends with toothpicks.
Place on a rack in a shallow roasting pan; spread with mustard mixture. Roast until meat reaches desired doneness (for medium-rare, a thermometer should read 135°; medium, 140°; medium-well, 145°), 40-50 minutes.
Remove roast from oven; tent with foil. Let stand 15 minutes before slicing. Remove string and toothpicks. Top servings with remaining cheese. If desired, warm additional onions in microwave and sprinkle over tops.
