1. Preheat oven to 375°.
2. Combine sweet potato, parsnip, carrot, 2 tablespoons vinegar, olive oil, and salt in a large bowl; toss well. Arrange vegetable mixture in a single layer on a foil-lined jelly-roll pan; bake at 375° for 30 minutes or until lightly browned, stirring occasionally. Set aside.
3. Cook pancetta in a Dutch oven over medium-high heat 8 minutes or until crisp. Remove from pan with a slotted spoon; set aside. Add shallots and onion to drippings in pan; cook 15 minutes or until golden. Add thyme, garlic, remaining 1 tablespoon vinegar, and pepper, and cook 1 minute. Add wine, scraping pan to loosen browned bits. Add pancetta, lentils, and 4 cups broth to pan; bring to a boil. Cover, reduce heat, and simmer 30 minutes. Add remaining 2 cups broth and roasted vegetables to pan, and simmer, uncovered, 15 minutes. Add chard, and cook 2 minutes or until wilted.