Add all of the ingredients (except the spinach and lemon juice) to a slow cooker. Mix to combine. Cover and cook on high for 5-6 hours or low for 7-8 hours - or until the veggies & lentils are tender.
Add the spinach and mix until wilted. Taste and adjust the seasonings as needed - add salt and lemon juice to your taste.
Spoon into bowls and enjoy!
Video
Notes
Be sure to rinse and pick through the lentils before adding them to the slow cooker. You can sub green lentils.
Since we aren't pre-cooking any of the veggies, you want them to be on the smaller side and for them to have a similar shape. This will ensure they cook fully and at the same time.
The vegan beef broth adds A LOT of flavor. If you need to use a different broth, you may need to add additional seasonings to the soup.
For stovetop: heat some oil in a stock pot over medium heat. Add the carrots, celery, onion, garlic & dry seasonings. Cook down for 3-5 minutes, or until they start to get tender. Pour in the broth, tomatoes & lentils. Bring to a boil, cover, lower the heat and simmer for 20-30 minutes (or until the veggies & lentils are tender). Stir in the spinach and adjust the seasonings as needed.
To freeze: allow the soup to cool completely, transfer to freezer-safe containers and keep in the freezer for 3-4 months.