Coat the bottom of a large pot with the oil and place it over medium heat. Give the oil a minute to heat up, then add the diced onion, carrots, and celery. Sweat the vegetables for about ten minutes, stirring often, until they begin to soften.
Stir in the garlic, curry powder, and ground cumin. Cook the mixture for about one minute, stirring constantly, until the garlic and spices become very fragtant.
Stir in the broth and lentils. Raise the heat and bring the liquid to a boil, then lower the heat and let the soup simmer for about ten minutes.
Stir in the kale. You may need to add it in batches, stirring in a handful at a time and letting it wilt before adding another handful. The volume of the kale will reduce quite a bit as it wilts. Bring the soup back to a simmer and let it cook for about fifteen minutes, until the kale and lentils are tender.
Stir in the tomatoes and let the soup simmer for five minutes longer.
Remove the pot from heat and season the soup with salt and pepper to taste.
Ladle the soup into bowls and serve.