Enjoy this potato soup as we prepared it with the potatoes unpeeled and unblended, or puree for an elegant presentation.
Heat oil and butter in a large stockpot over medium heat. Add the celery, carrots and leeks and stir well. When the vegetable mixture softens and becomes somewhat translucent, stir in the chopped potatoes with the vegetables. Add the chicken stock and salt and pepper to taste. Bring the mixture to a boil and then reduce the heat to a simmer and cover. Allow the soup to continue to cook until the potatoes are tender but not mushy. Stir in the chopped endive or escarole and cook for an additional 3 minutes. Serve immediately.