Pour the olive oil into a dutch oven over medium heat. Add in the onions, carrots and garlic and cook for 3-4 minutes until the onions are translucent. Add in the cumin and coriander and cook for an additional minute until fragrant.
Next add in the lentils, crushed tomatoes, broth, salt and pepper and stir to combine. Bring this to a simmer and cook the soup for 20 minutes or until the lentils are soft. Stir in spinach and lemon juice and serve as desired.
