In a large soup pot or Dutch oven, heat the canola oil over medium heat. Add the chopped onion, carrots and celery and season with salt and pepper. Cook for about 5-7 minutes until the vegetables start to soften.
Add the turmeric and stir. Then add the lentils and broth. Bring to a boil. Reduce heat to medium-low and simmer for 20-25 minutes until the lentils are soft.
Add the spinach and cook until wilted if using fresh, about 1-2 minutes, or for about 5 minutes if using frozen.
Serve hot and enjoy.