Add vegetable oil into a large saucepan and heat over medium high heat. Add onions, sprinkle with cumin and cook until onions begin to sauté, about 5-7 minutes. Add 3 cloves minced garlic and sauté for 1 more minute.
Add lentils and chicken broth into saucepan and bring to a boil. Cover with a lid, reduce to low heat and simmer for 30 minutes, or until lentils are soft.
Add diced tomatoes, salt, pepper, 1 clove minced garlic and kale to saucepan and stir. Cover and continue to simmer for 10 minutes, or until kale is wilted.