Place lentils in a pot with 3 cups water. Bring to a boil, reduce heat to low, and cook 20 minutes or until tender. Drain and set aside.
Bring rice and 1 1/3 cup water to boil in a pot. Reduce heat, cover, and simmer for 20 minutes.
Heat oil in a skillet over medium heat. In a bowl, combine the ground beef, beaten egg, garlic, 1 tablespoon Parmesan cheese, parsley, bread crumbs, salt, and pepper. Form ground beef mixture into 1 inch balls. Place meatballs in skillet and cook 5 minutes or until evenly brown.
In a large pot, bring the tomato sauce and 4 cups water to a boil. Transfer the browned meatballs to the pot. Mix in cooked lentils and rice. Return to a boil, reduce heat to medium-low, and simmer for 30 minutes. Sprinkle with remaining Parmesan cheese to serve.