How to Make It
Cook bacon pieces in a large Dutch oven over medium-high, stirring often, until crisp, about 10 minutes. Drain on paper towels, and set aside. Remove and discard all but 2 Tbsp. drippings from Dutch oven.
Add onion, celery, and garlic to Dutch oven. Cook over medium-high, stirring often, until softened, about 5 minutes. Add cumin, and cook, stirring constantly, until toasted, about 1 minute. Stir in sweet potato, lentils, broth, tomatoes, salt, and pepper. Bring to a boil over medium-high. Reduce heat to medium-low; simmer until lentils are tender, 45 to 50 minutes. Spoon soup evenly into 6 bowls. Top with reserved bacon pieces, and sprinkle with parsley.