Creamy Turnip Soup

Name: Creamy Turnip Soup
Ingredients: 4 medium turnips (about 1 1/2 pounds) plus 1 1/2 cups thinly sliced turnip greens or spinach, divided; 2 tablespoons extra-virgin olive oil, divided; 1 tablespoon butter; 1 medium onion, sliced; ½ teaspoon dried rosemary; ½ teaspoon salt plus a pinch, divided; ¼ teaspoon freshly ground white pepper plus a pinch, divided; 4 cups reduced-sodium chicken broth; ¼ cup shredded carrot; 2 tablespoons thinly sliced scallion greens; 2 teaspoons white-wine vinegar