Place the red and brown lentils in a pan with the water and turmeric. Cook over medium-low heat until tender, about 45 minutes. Drain, reserving 2 1/2 cups of the cooking liquid.
Meanwhile, heat the canola oil in a large, deep pot over medium heat. Stir in the onion, and cook until tender and transparent, about 5 minutes. Stir in the tomatoes and garlic; cook 5 minutes more, stirring occasionally. Mix in the curry powder, cumin, salt, pepper, and cloves. Add the cooked lentils, reserved cooking liquid, pumpkin, potatoes, and carrots. Cover, and cook over medium-low heat until the vegetables are tender, 35 to 45 minutes. Stir in the spinach and apple. Cook until the pumpkin can be easily pierced with a fork, about 15 minutes more. Adjust seasonings to taste.