Hot and sour soup is probably one of the most common menu item in Chinese restaurants across north America, next to things like spring roll and beef and broccoli. But it is not something that is all that common in Asia outside of noodle and dumpling houses specialized in northern Chinese style fare. Growing up in a Shanghainese household, I can probably count the number of times my grandparents or parents cooked this dish with one hand. But I always enjoy it whenever it is on the table, at home or in restaurants.
It is not hard to see why it is so popular in American Chinese restaurants. The salty, spicy and mild acidity (not easy to find examples of properly sour bowls ...) bring a welcome respite to the often bland and sweet dishes at these places. What is not well known is that, it is dead simple to make at home, just don't be shy with the vinegar and the white pepper. Another tip is to cook the tofu and pork (finely chopped tenderloin works well here) after the soup has been thickened, they stay more tender that way.