Prepare the vegetables: Dice the yellow onion, carrot, and potato. Slice the cremini mushrooms. Mince garlic.
In a stockpot over medium-high heat, sauté onion for 5 minutes. Use 3 Tbsp. water/broth for a no-oil-sauté method, adding more as needed.
Then add the carrot, potato, and mushroom to the pot. Stir and sauté for 3-4 more minutes.
Add the garlic and Italian seasoning. Stir and sauté for 1 minute.
Add 6 cups of broth. Increase heat and bring to a light boil.
Once boiling, add lentils (rinsed & drained). Cover and reduce heat to a simmer. Simmer for 30 minutes or until lentils are tender.
Stir in tamari and spinach (roughly chopped) during the last couple of minutes of cook time. Add salt & pepper to taste if desired.
