Sweet Potato and Black Bean Burritos

Heat 1 Tbsp of the oil in a large skillet over medium heat. Add the sweet potato, chopped onion and 1/2 tsp salt and cook, covered, stirring occasionally, until tender, 10 to 12 minutes. Add the beans and chipotles and cook, stirring occasionally, for 2 minutes. Add the spinach and cook, tossing, until it begins to wilt, 1 to 2 minutes. Divide the cheese and potato-bean mixture among the tortillas (about 1 cup each) and roll up to form burritos. Wipe out the skillet and heat over medium heat. Cook the burritos (seam-side down first) until golden brown, 2 to 3 minutes per side. Meanwhile, in a medium bowl, whisk together the sour cream, lime juice, remaining Tbsp oil, and 1/4 each tsp salt and pepper. Add the romaine and sliced onions and toss to coat. Serve with the burritos and lime wedges, if desired.