Step 1

Heat olive oil in a large sauté pan over medium heat. When oil is shimmering, add onion, carrots, and celery and cook, stirring periodically, until vegetables start to soften, about 5 minutes. Add garlic cook, stirring, until fragrant, about 1 minute. Stir in cumin, cayenne, and paprika, and continue cooking until fragrant.

Step 2

Transfer mixture to a slow cooker. Add lentils, bay leaves and 12 cups of stock. Season with about 1 teaspoon of salt, stir to combine, and cover. Set slow cooker to low and cook for 4 hours, stirring hourly and adding in additional broth as needed to maintain a loose, soup-like consistency.

Step 3

When the soup is done, discard bay leaves, transfer to a blender or food processor, and add vinegar. Adjust seasonings, if needed, and purée until smooth. Ladle into bowls and top with red onion and cilantro, and serve with lemon wedges.