This soup offers another dimension to the idea of ‘Chestnuts roasting on an open fire.’
Rich and satisfying, it makes a great starter for a special holiday dinner, or it can double as an easily-made... winter treat if chemo or radiation have brought you down, and you need some healthy comfort and some extra calories to sustain you.
Heat the olive oil in a stockpot over medium heat. Add the onion, fennel, garlic, and celery. Sprinkle with salt and pepper. Cook until the onions begin to turn translucent, then cover and let sweat for 15 minutes.
Meanwhile, make a bouquet garni by putting the thyme, bay leaf, cloves and sage leaves into a square of cheese cloth and tying it closed from the corners.
Add the chestnuts to the onion mixture and cook, stirring occasionally, for 5 minutes. Add the bouquet garni and broth. Bring to boil, then simmer for 20 minutes.
Add the vinegar and cook for 3 minutes. Remove the herbs, puree the soup, and heat through. Stir in the yogurt. Taste for seasoning.
If you can’t find the vacuum packed chestnuts or a jar, look for unsweetened chestnut puree and stir it into the soup after the other ingredients have been pureed in step 4. Return the bouquet garni to the soup. Cook 5 -10 minutes to heat the puree through at a low simmer and to blend the flavors. Stir frequently to make sure the soup doesn’t stick. Remove the herbs before serving.