Heat oven to 425°F. Combine onions, Brussels sprouts, oil and 1 teaspoon salt on metal baking pan; toss to coat. Set aside.
Combine thyme and pepper in small bowl. Reserve 1 teaspoon thyme mixture for sauce; set aside. Press remaining thyme mixture evenly onto all surfaces of beef Tenderloin Roast.
Place roast on rack in shallow roasting pan. Insert ovenproof-meat thermometer so tip is centered in thickest part of beef. Do not add water or cover. Place prepared vegetables in oven with roast. Roast beef in 425°F oven 35 to 45 minutes for medium rare; 45 to 50 minutes for medium doneness. Roast vegetables 45 to 50 minutes or until tender and lightly browned
Meanwhile, prepare sauce. Combine vinegar and shallots in small saucepan; bring to a boil. Reduce heat; simmer 3 minutes. Stir in cranberry sauce; bring to a boil. Reduce heat; simmer 6 minutes to blend flavors, stirring occasionally. Remove from heat; stir in reserved 1 teaspoon thyme mixture and remaining 1/4 teaspoon salt. Keep warm.
Remove roast when meat thermometer registers 135°F for medium rare; 145°F for medium. Transfer roast to carving board; tent loosely with aluminum foil. Let stand 15 to 20 minutes. (Temperature will continue to rise about 10° to 15°F to reach 145°F for medium rare; 160°F for medium.)
Carve roast into slices; serve with vegetables and sauce.
Nutrition information per serving: 286 Calories; 71.1 kcal Calories from fat; 7.9 g Total Fat; 2.8 g Saturated Fat; 0.34 g Trans Fat; 0.8 g Polyunsaturated Fat; 3.6 g Monounsaturated Fat; 71 mg Cholesterol; 319 mg Sodium; 29.3 g Total Carbohydrate; 5 g Dietary Fiber; 27.5 g Protein; 4.4 mg Iron; 754.8 mg Potassium; 5.5 mg NE Niacin; 0.9 mg Vitamin B6; 3.5 mcg Vitamin B12; 4.1 mg Zinc; 23.1 mcg Selenium; 81.9 mg Choline;