Add the red lentils, vegetable broth, water, salt, and black pepper. Stir and increase the heat to high. Bring the mixture to a boil. Immediately reduce the heat to medium-low, cover, and simmer for 20-25 minutes, or until the soup thickens and the lentils have broken down and are soft. Add the baby spinach and baby kale. Stir and remove from heat. Add more salt if needed.