Place lentils in a pot with 3 cups (750ml) 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 (325ml) water to boil in a pot. Reduce heat, cover, and simmer for 20 minutes.
Heat oil in a frypan over medium heat. In a bowl, combine the beef mince, beaten egg, garlic, 1 tablespoon Parmesan cheese, parsley, breadcrumbs, salt, and pepper. Form beef mince mixture into 2 cm balls. Place meatballs in frypan and cook 5 minutes or until evenly brown.
In a large pot, bring the tomato sauce and 1 litre 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.