Preparation

• Cut 1 quarter from one of the apples.Wrap the unpeeled quarter in plastic wrap and reserve. Peel, core, and quarter the rest of the apples. Chop the peeled apples into 1/2-inch pieces and toss with the lemon juice in a medium bowl.
• Heat the olive oil in a heavy-duty 4-quart saucepan over medium-low heat. Add the leeks and onion and cook, covered, stirring occasionally with a wooden spoon, until just tender, 6 to 8 minutes.
• Stir in the ginger, tomato paste, garlic, and curry powder and cook, stirring, until fragrant, about 1 minute. Add the vermouth and cook, uncovered, stirring occasionally, until the liquid has almost evaporated, 2 to 3 minutes.
• Add the chopped apple, parsnips, and potatoes and stir to coat well. Add the chicken broth and 1-1/2 tsp. salt and bring to a boil over medium-high heat, stirring occasionally. Reduce the heat to medium low, partially cover, and simmer, stirring occasionally, until the apples and vegetables are very tender, about 30 minutes.
• In a blender, purée the soup in batches until completely smooth. Transfer the soup to a clean 4-quart saucepan, stir in the cream, and season to taste with salt and white pepper. Bring the soup to a simmer over medium heat, stirring often. Cut the reserved apple quarter into small dice. Serve the soup sprinkled with the diced apple and chives.

Make Ahead Tips

The soup can be made 2 days ahead and kept covered and refrigerated. Reheat it gently and garnish just before serving.