1. Brown the sausage: In a large skillet over medium-high heat, heat the olive oil. Add the Italian sausage and cook, breaking it up with a spatula, until browned and no longer pink. Transfer the sausage to the slow cooker with a slotted spoon, leaving a little of the drippings in the pan.

2. Sauté the vegetables: Add the diced onion, carrots, and celery to the same skillet. Cook for 4–5 minutes, stirring often, until the vegetables begin to soften and pick up some color. Stir in the minced garlic and cook for 30 seconds, just until fragrant. Transfer the vegetable mixture to the slow cooker.

3. Add lentils and seasonings: To the slow cooker, add the rinsed lentils, diced tomatoes with their juices, tomato paste, Italian seasoning, smoked paprika, bay leaf, salt, and pepper. Pour in the chicken broth and stir everything well to combine.

4. Slow cook: Cover and cook on LOW for 7–8 hours or on HIGH for 3–4 hours, until the lentils are tender and the soup has thickened slightly. If the soup becomes thicker than you like, stir in extra broth or hot water to loosen it.

5. Finish the soup: Remove the bay leaf. Stir in the chopped fresh parsley and taste the soup, adjusting with additional salt and pepper as needed.

6. Serve: Ladle the hot soup into bowls and garnish with extra parsley if desired. Serve with crusty bread, a green salad, or your favorite cozy sides.