In a large saucepan heat oil over medium-low heat. Add onion, carrots, and garlic. Cook, covered, for 5 to 7 minutes or until vegetables are nearly tender, stirring occasionally.
Add broth and, if using, dried basil to vegetable mixture. Bring to boiling; reduce heat. Simmer, covered, for 10 minutes. Stir in kale, salt, and black pepper. Return to boiling; reduce heat. Simmer, covered, for 10 minutes.
Stir in chicken, tomato, lentils, and, if using, fresh basil. Simmer, covered, for 5 to 10 minutes more or until kale and lentils are tender. Makes 6 servings.