Celery and Walnut Pies

These light little pies should be served hot but they can be made ahead and re-heated. Serve them, if you like, as a first course; I make a cold sauce to accompany them from a can of chopped tomatoes, seasoned with a real bite of cayenne pepper (chilli powder) and a little lemon juice; or serve them as something to nibble during one of the drinking moments of Christmas. The pies have a flaky, che