Preheat oven to 350°.
Combine sweet potato and broth in a large nonstick skillet. Bring to a simmer over medium-low heat; cover and cook 7 minutes or until tender. Add onion and garlic; cook 2 minutes. Add corn, black beans, bell pepper, cilantro, and lime juice; simmer, uncovered, 6 minutes or until thoroughly heated. Combine sweet potato mixture and refried beans in a medium bowl. Spoon about 1/2 cup sweet potato mixture down center of each tortilla, and roll up. Place burritos in a 13 x 9-inch baking dish; cover with foil.
Bake at 350° for 15 minutes or until thoroughly heated. Serve each burrito with 1 tablespoon sour cream and 1 tablespoon salsa. Sprinkle each burrito with 1 teaspoon chopped cilantro, if desired.