How to Make It
Heat the oil in a large pot or Dutch oven over medium heat. Add the celery, carrots, onion, and garlic. Cook, stirring occasionally, until softened, 8 to 10 minutes.
Add the kielbasa, lentils, 8 cups water, and ½ teaspoon each salt and pepper and bring to a boil. Reduce heat and simmer, stirring occasionally, until the lentils are tender, 35 to 45 minutes.
Serve warm sprinkled with the parsley.