In Dutch oven, heat oil over medium heat; cook onion, garlic and ginger, stirring occasionally, until softened, about 5 minutes.
Add carrot, cumin and cinnamon; cook, stirring occasionally, until fragrant, about 3 minutes. Stir in lentils to coat.
Add broth and bring to boil; reduce heat, cover and simmer until lentils are al dente, about 10 minutes.
Add kale and raisins; simmer, covered, until lentils are tender, about 10 minutes. Uncover and cook until almost no liquid remains, about 4 minutes. Sprinkle with walnuts.