Preheat oven to 450ºF (230ºC). Rub roast with half the oil. Season with paprika, salt and garlic. Place in roasting pan. Add onions, carrots and peppers to pan and drizzle with remaining oil. Mix to coat veggies with oil and spread them around roast. Roast 15 min. Reduce heat to 375ºF (190ºC). Roast another 60 to 90 min., or until meat thermometer inserted in centre registers 145°F (63ºC) for medium-rare. Remove from oven. Transfer roast to cutting board, cover loosely with foil and rest 15 min. Transfer vegetables to bowl.
Place roasting pan on stove top over medium heat. Stir in tomato sauce and bring to a boil. Reduce heat to low. Simmer 5 min. Add roasted vegetables back into pan. Stir in parsley.
Thinly slice roast and serve with vegetable ragu.