Hot and Sour Soup
(from The Thousand Recipe Chinese Cookbook 
by Gloria Bley Miller)

    3-4 dried black mushrooms
    1/4 pound lean pork
    2 bean curd cakes (I use 8oz of extra firm)
    1 scallion
    1 egg
    2 Tbsp. cornstarch
    1/4 cup water
    5 cups stock
    1 cup mushroom soaking liquid
    1 Tbsp. sherry
    2 Tbsp. white vinegar
    3/4 tsp. salt
    1 tsp. soy sauce
    1/4 tsp. pepper
    few drops of sesame oil

1. Soak dried mushrooms and reserve soaking liquid

2. Sliver mushrooms, pork and bean curd.  Mince scallion.
   Bead egg lightly.  Blend cornstarch and water to a paste.

3. Bring stock and mushroom liquid to a boil.  Add pork and
   mushrooms an simmer, covered, 10 minutes.

4. Add bead curd and simmer, overed, another 3 minutes.

5. Stir in sherry, vinegar, salt, soy sauce and
   pepper. Thicken with cornstarch paste.

6. Slowly add beaten egg, stirring once or twice.  Remove from
   heat.  Sprinkle with sesame oil and minced scallion.

Variations: 
 + for the pork, use half white0meat chicken and half pork.
 + for white vinegar, substiture wine or cider vinegar, or 
   lemon juice.
 + for sesame oil, substitute Tabasco sauce
 + in step 3 (in addition to pork and mushrooms), add 
   1/2 cup bamboo shoots, slivered; or 4 cloud ear mushroooms 
   and 1/4 cup lily bud (both soaked and cut in half)
 + omit venegar and pepper (it's then called Mandarin soup)