- 3 lb butternut squash (1 large), halved lengthwise and seeds discarded
- 1 tablespoon olive oil
- 2 lb sweet potatoes (2 large)
- 1 large onion, chopped
- White part of 1 leek, chopped
- 2 teaspoons chopped peeled fresh ginger
- 8 to 10 cups light vegetable stock or broth
- White pepper to taste
- 2 to 3 tablespoons fresh lemon juice, or to taste
- 1 tablespoon honey (optional)
- Chipotle sauce
- Preheat oven to 400°F.
- Brush cut sides of squash with 1/2 teaspoon oil and arrange, cut sides down, in a shallow baking pan. Prick sweet potatoes all over with a fork and roast with squash until very tender, about 50 minutes for squash and about 1 1/4 hours for sweet potatoes.
- Cool vegetables and scoop flesh from squash into a bowl. Peel sweet potatoes and add to squash.
- Cook onion in remaining 2 1/2 teaspoons oil with salt to taste in a 6-quart heavy pot over moderately high heat, stirring occasionally, until golden brown, about 10 minutes. Stir in squash and sweet potato, leek, ginger, and 8 cups stock and simmer, uncovered, stirring occasionally, 30 minutes.
- Purée in batches in a blender (use caution when blending hot liquids), transferring to a clean pot. Bring to a simmer and, if too thick, add more stock. Season with salt and white pepper. Finish with lemon juice and, if desired, honey.
- Serve soup drizzled with some chipotle sauce or swirl sauce in to make a pattern.