Heat the 1 tablespoon of oil or 3 tablespoon of broth or water in a stock pot on medium heat. When the oil is hot, add the onion and carrots. Sauté for 5 minutes to 7 minutes, or until the onion is translucent. Stir frequently.
Add the garlic, rosemary, and rinsed lentils to the pot and stir. Cook for 2 minutes.
Add the broth and 2 cups of water and bring to a boil, then reduce the heat to simmer.
Crush the 2 teaspoon of Italian seasoning into the soup and season to your liking with salt and pepper. Stir to combine.
Cook for 25-30 minutes or until the carrots and lentils are soft, but not mushy.
Add the spinach and the lemon juice and stir. The soup is ready when the spinach has wilted.
Enjoy!