1 tbsp olive oil
1 medium yellow onion, finely chopped
1 medium carrot, finely chopped
1 stalk celery, finely chopped
1 leek, chopped
4 cloves garlic, minced
1 sprig fresh rosemary, minced
1 cup green or brown lentils, rinsed
2 cups cremini mushrooms, sliced
1 sweet potato, diced
1 tbsp balsamic vinegar
1 tbsp tamari
4 cups vegetable stock, divided
salt and pepper, to taste
1. In a large, heavy soup pot, heat olive oil over medium heat. Add the onions, carrots, celery, and leek to the pot and stir. Cook and stir until the onions are quite soft, about 5 minutes.
2. Add the garlic and rosemary and cook for 30 seconds, or until fragrant.
3. Add the lentils and stir to coat.
4. Add the mushrooms and sweet potato and stir to coat.
5. Add the balsamic vinegar, tamari, and vegetable stock. Scrape up any brown bits that have accumulated.
6. Bring the lentils to a boil, then reduce heat to a simmer. Cover and cook until lentils and sweet potato are just tender and there is just enough liquid to keep the mixture thick and stew-like, about 15 to 20 minutes. Season with salt and pepper.