I've never had H&S with chinese okra, but it's possible some use it. Certainly the description is like what you describe.

Light green or dark green?

Good luck finding it out! I'm curious to hear what it is.

Darn, another seed I'll have to come up with:)

I got an idea while looking through earlier posts. It could very well be preserved vegetable (either kohrabi or chinese (oriental) mustard is used for preserved vegetable. Both are a dull green colour, and likely conforms texturewise to what you had. Preserved vegetables are often julienned or diced and added to a variety of soups and main dishes to add subtle flavour. Not many prople realize it is often an ingredient in many Chinese broths and soups. It makes sense, also, as this is a Szechuan product and so lines up with the s&s soup.

HOT 'N SOUR SOUP

4 Dried Chinese mushrooms, -1 to 1 1/2 in dia ( or canned straw mushrooms
2 Squares, 3 inches each,fresh Chinese bean curd, about -1/2 inch thick (tofu)
1/2 c Canned bamboo shoots
1/4 lb Boneless pork
1 qt Chicken stock, fresh or canned
1 t Salt
1 Scallion, including the green top, finely chopped
1 tb Soy sauce
1/4 ts Ground white pepper
2 tb White vinegar
2 tb Cornstarch* mixed with 3 tablespoons cold water
1 Egg, lightly beaten
2 ts Sesame seed oil

* if soup is not thick enough, add 2 more spoons of
cornstarch (mixed into cold water) into the soup

PREPARE AHEAD:
1. In a small bowl, cover the mushrooms with 1/2 cup
of warm water and let them soak for 30 minutes.
Discard the water. With a cleaver or knife, cut away
and discard the tough stems of the mushrooms, and
shred the caps by placing one at a time on a chopping
board. Cut them horizontally into paper-thin slices,
and then into thin strips. 2. Drain the pieces of
bamboo shoots and bean curd, and rinse them in cold
water. Shred them as fine as the mushrooms. 3. With
a cleaver or sharp knife, trim the pork of all fat.
Then shred it, too, by slicing the meat as thin as
possible and cutting the slices into narrow strips
about 1-1/2 to 2 inches long. 4. Have the above
ingredients, stock, salt, soy sauce, pepper, vinegar,
cornstarch mixture, egg, sesame seed oil and scallions
within easy reach. TO COOK: Combine in a heavy
3-quart saucepan the stock, salt, soy sauce,
mushrooms, bamboo shoots and pork. Bring to a boil
over high heat, then immediately reduce the heat to
low, cover the pan and simmer for 3 minutes. Drop in
the bean curd and the pepper and the vinegar. Bring to
a boil again. Give the cornstarch mixture a stir to
recombine it and pour it into the soup. Stir for a
few seconds until the soup thickens, then slowly pour
in the beaten egg, stirring gently all the while.
Remove the soup from the heat and ladle it into a
tureen or serving bowl. Stir in the sesame seed oil
and sprinkle the top with scallions. Serve at once.

http://www.lsxc.com.cn/2005/3-17/101421.htm

And you may also be pleasantly surprised at your restaurant's willingness to tell you what the ingredient is, especially if you tell them you really like it (NOT that you want to know because you want to grow it yourself & make your own soup - LOL!!!)

For my Hot & Sour Soup I simply combine:

Shitake mushrooms - fresh or rehydrated dried, sliced
Dried Wood Ears - rehydrated, sliced if large
Dried Lily Buds - rehydrated & tied into single knots
Extra Firm Bean Curd - cubed
Chicken stock - brought to a low boil
Boneless, skinless chicken breast - cut into julienne strips
One or 2 beaten eggs
Fresh scallions, chopped
White vinegar to taste
Freshly ground black pepper to taste

If I have it on hand I will also add some chopped or julienned bok choy.

I keep bowls of this in the fridge for a quick lunch or supper - yum!!

Which restaurant and what city? Maybe I can go check it out.

;)

http://en.wikipedia.org/wiki/Zha_cai

Pickled Mustard Root or Zha Cai

This site also says it is essential for H&S soup: http://makantime.com/ingredientguide/zhacai.htm

Try it!