Chestnut Soup with Sourdough Sage Croutons

Directions

1. 1.

   Put oven rack in upper third of oven and preheat oven to 375°F.

2. 2.

   Spread chestnuts in 1 layer in a large shallow baking pan, then roast in oven until dry and slightly darkened, about 20 minutes.

3. 3.

   While chestnuts roast, wash leeks in a bowl of cold water, agitating them, then lift out and drain well.

4. 4.

   Heat oil and butter in a 5- to 6-quart heavy pot over moderately high heat until foam subsides, then sauté leeks, onion, celery, carrots, and bay leaves, stirring occasionally, until vegetables are pale golden, 8 to 10 minutes. Add chestnuts and tamari and cook, stirring, until most of liquid is evaporated, 1 to 2 minutes. Add water (2 1/2 quarts) and salt and simmer, uncovered, stirring occasionally, until vegetables are tender, about 30 minutes. Remove from heat and stir in parsley and sage. Discard bay leaves.

5. 5.

   Purée soup in 3 batches in a blender until smooth (use caution when blending hot liquids), transferring to a bowl. Pour purée through a medium-mesh sieve into cleaned pot, pressing hard on and then discarding solids. Bring soup to a simmer and stir in Sherry, pepper, and salt to taste, then remove from heat.

6. 6.

   Heat oil and butter in a 12-inch heavy skillet over moderately high heat until foam subsides, then cook bread cubes with sage, turning occasionally, until croutons are golden, 6 to 10 minutes. Add chestnuts and cook, stirring, 2 minutes. Transfer to a large bowl and toss with sea salt.

7. 7.

   Ladle soup into bowls and sprinkle each serving with about 1/3 cup topping.