In a medium pot over medium heat, sauté the carrot and onion and cook until the onion is translucent, about 2 minutes.
Add the garlic, tomatoes, red pepper, green pepper and sauté until the vegetables are soft, about 3 minutes. Add the cumin, chili powder, salt and pepper.
Add the lentils, the broth and tomato paste, increase the heat to high and bring to a boil.
Reduce the heat to low, cover and simmer until the lentils are tender about 25 minutes. Add the potatoes and cook for about 10 minutes more.
Add the spinach and simmer for about 2 minutes more. Season the soup with salt and pepper.
Serve warm with plain white rice.