How to make a restaurant style meatless Hot and Sour Soup I made a hot-and-sour soup based on an online recipe, omitting the pork, sugar and dried lilly buds.

The major flavoring components were:


1tsp White pepper (I used a supermarket-grade pre-ground variety)
2tblsp premium brand red wine vinegar
1tblsp good soy sauce
1tsp Sesame oil
1tsp Salt 
Small package (3oz) assorted dried and reconstituted wild mushrooms
4c Chicken stock as the base


I also added a tablespoon of Asian chili-garlic paste for extra heat.

The color was pale clear, not the rich brown or reddish-orange I'm used to at Asian restaurants. It smelled terrible - a definite barnyard odor once the white pepper was added. The taste was off as well - instead of a pleasing tangy heat, it was vinegary in an unpleasant way without being tangy, and not particularly hot despite some extra white pepper and chili-garlic paste. 

While I can fix the heat (more chili paste!), I'm not certain how to fix the sour, the color or the aroma.

(Note: I cannot add sugar or solid meat to this dish for medical reasons. Sugar substitute should be OK, if that will really fix it.)
For heat, I recommend chili oil as opposed to a paste. That and white pepper should give you a pretty solid heat component. Even though the thought initially made me go EEEEEEW, ATK does recommend a a 50/50 combination of Balsamic and red wine vinegars as a replacement for the ideal Black Chinese Vinegar, which is probably what great Chinese restaurants use. Do you eat eggs? If so, I'd certainly use one. Here's the technique, again from ATK " Without stirring soup, use soupspoon to slowly drizzle very thin streams of egg mixture (1/2 tsp corntarch, 1 tsp water beaten with 1 egg) into pot in circular motion. Let soup sit 1 minute, then return saucepan to medium-high heat. Bring soup to gentle boil, then immediately remove from heat. Gently stir soup once to evenly distribute egg."

You probably should considerably up your soy sauce. Consider too your mushrooms. "Assorted" can mean just about anything. Some mushrooms are very strongly flavored in a way that just plain clashes with Chinese Hot and Sour. That could very well account for the barnyard odor you describe. I'd recommend sticking to shiitake/oyster/woodear if you can.