Source: The New York Times - November, 2007
Peel and core 2 1/2 apples and place in 3-quart saucepan with fennel, shallot, celery, stock, wine, salt and pepper. Simmer 20 minutes, until all are tender.
Meanwhile, core and finely dice remaining half apple, toss with half the lemon juice, cover tightly and set aside.
Purée contents of saucepan in a blender; return to pot. Whisk in remaining lemon juice, cream and mustard. Bring to a simmer, check seasonings and serve, with diced apple garnishing each portion.