Chop the onion, celery, carrots, and potatoes into fairly even 1/2–3/4 inch pieces. Rinse the dried green or brown lentils in a fine-mesh strainer under cool water until the water runs mostly clear. Drain well.
1 1/2 cups dried green or brown lentils, 4 medium carrots, 3 medium potatoes, 1 medium yellow onion, 3 stalks celery
In a 5–7 quart slow cooker, add the rinsed lentils, sliced carrots, diced potatoes, chopped onion, sliced celery, minced garlic, diced tomatoes with their juices, tomato paste, vegetable broth, water, ground cumin, smoked paprika, dried thyme, bay leaf, salt, black pepper, and olive oil if using. Stir well to dissolve the tomato paste and distribute the spices evenly.
1 1/2 cups dried green or brown lentils, 4 medium carrots, 3 medium potatoes, 1 medium yellow onion, 3 stalks celery, 4 cloves garlic, 1 can (14.5 oz) diced tomatoes, 4 cups vegetable broth, 1 cup water, 2 tablespoons tomato paste, 2 teaspoons ground cumin, 1 1/2 teaspoons smoked paprika, 1 teaspoon dried thyme, 1 bay leaf, 1 teaspoon fine sea salt, 1/2 teaspoon black pepper, 2 tablespoons olive oil
Cover the slow cooker and cook on LOW for 7–8 hours or on HIGH for 3 1/2–4 hours, until the lentils are tender and the potatoes are soft but not falling apart. Check toward the earlier time the first time you make this, as slow cookers can vary.
When the lentils and vegetables are tender, remove and discard the bay leaf. Stir in the chopped kale or baby spinach and let it wilt in the hot stew for 5–10 minutes. Add 1 tablespoon of lemon juice, taste, and add up to 1 additional tablespoon if you prefer more brightness. Adjust salt and pepper to taste.
1 bay leaf, 2 cups chopped kale or baby spinach, 1 tablespoon lemon juice, 1 teaspoon fine sea salt, 1/2 teaspoon black pepper
If the stew is thicker than you’d like, stir in additional hot water or vegetable broth, 1/4 cup at a time, until it reaches your preferred consistency. If it’s too thin, cook uncovered on HIGH for 20–30 minutes to reduce slightly.
Ladle the stew into bowls. Top with chopped fresh parsley or cilantro, a pinch of red pepper flakes, and a swirl of vegan yogurt or cashew cream if desired. Serve on its own or with crusty bread, cooked rice, or quinoa.
fresh parsley or cilantro, red pepper flakes, unsweetened vegan yogurt or cashew cream, crusty bread, cooked rice, or quinoa