In a large pot or Dutch oven, cook sausage over medium-high heat until crumbled and browned, about 8 minutes. Transfer meat to a bowl; drain all but 1 tablespoon drippings.
Add onion, celery, carrots, and garlic to pot with drippings; season with 1 teaspoon salt and cook over medium until softened, about 5 minutes. Add tomato paste and cook 1 minute.
Rinse lentils in a fine-mesh strainer then add to pot along with 7 cups water, tomatoes, and Worcestershire, if using. Bring to a boil over high heat, then reduce a simmer over medium and cook, partially covered, until lentils are tender, 30–35 minutes.
Stir in kale by handful and simmer until wilted. Stir in sausage, parsley and 1–2 more cups of water as needed. Season with salt and pepper to taste.