Curried Carrot Apple Soup

1 tablespoon extra-virgin olive oil
1 large onion, chopped (2 cups)
1 stalk celery, finely chopped
1 tablespoon curry powder
5 large carrots, peeled and thinly sliced (3 cups)
2 large apples, peeled and coarsely chopped (3 cups), peeled and coarsely chopped (3 cups)
1 bay leaf
4½ cups reduced-sodium chicken broth
¼ teaspoon salt
Freshly ground pepper, to taste
Sour cream for garnish (optional)
1 tablespoon chopped fresh parsley, dill or basil for garnish (optional)

- Heat oil in a large saucepan or medium soup pot over medium heat. Stir in onion and celery; cook until the onion is softened and translucent, 8 to 12 minutes; do not brown.
- Stir in curry powder, then add carrots, apples and bay leaf. Stir well over medium heat for 2 minutes, then add broth and salt. Bring the mixture to a low boil, then reduce the heat to low. Cover tightly and simmer until the carrots and apples are tender, 20 to 25 minutes.
- Remove the bay leaf. Using a large slotted spoon, transfer the soup solids to a food processor, adding about 12 cup of the broth; process to a smooth puree. Pour the puree back into the soup.

- Reheat and season with pepper. 

- Serve piping hot, garnishing each serving, if you like, with a dab of yogurt and a sprinkle of fresh herbs.