Preparation Heat heavy medium skillet over medium-high heat. Add ground beef and cook until beef is brown, crumbling with fork, about 5 minutes. Drain well. Heat oil in heavy 3-quart saucepan over medium-high. Add onion and next 5 ingredients. Sauté until onion is tender, about 8 minutes. Add beef, lentils and next 8 ingredients to saucepan. Cover and simmer until lentils are tender, stirring occasionally, about 1 1/2 hours. Stir in Parmesan. Simmer, uncovered, until mixture is thick, about 15 minutes. Serve, passing sour cream separately.
Preparation Heat heavy medium skillet over medium-high heat. Add ground beef and cook until beef is brown, crumbling with fork, about 5 minutes. Drain well. Heat oil in heavy 3-quart saucepan over medium-high. Add onion and next 5 ingredients. Sauté until onion is tender, about 8 minutes. Add beef, lentils and next 8 ingredients to saucepan. Cover and simmer until lentils are tender, stirring occasionally, about 1 1/2 hours. Stir in Parmesan. Simmer, uncovered, until mixture is thick, about 15 minutes. Serve, passing sour cream separately.