In large saucepot, heat oil over medium-high heat. Add mushrooms, garlic, carrot, bell pepper and onion. Cook until vegetables are very brown and soft, about 15 to 20 minutes, stirring frequently.
Add wine; cook 1 minute, stirring constantly. Use wooden spoon to scrape browned bits from bottom of pan.
Stir in bay leaf, crushed tomatoes, water, lentils, oregano, salt, black pepper and red pepper flakes. Heat to boiling, then reduce heat to medium-low. Simmer until lentils are tender, about 25 minutes, stirring occasionally. Add more water, as needed, if ragu gets too thick. Remove bay leaf and stir in basil.
Meanwhile, prepare spaghetti according to package directions.
Serve ragu over spaghetti. Garnish with parsley and serve with Parmesan cheese.