The reason that Hot and Sour Soup is so thick is because the Hot and Sour Soup is thickened with cornstarch.
The addition of cornstarch is what makes the hot and sour soup thick.
Some people make the hot and sour soup thinner by adding less cornstarch or by adding no cornstarch.
If you make hot and sour soup and it's too thick then add less cornstarch or add no cornstarch.
Hot and Sour Soup is good for around 4 to 5 days in the refrigerator.
After 5 days or so the hot and sour soup will usually start going bad and growing bacteria in it so it should be eaten within a few days for the best taste and freshness.
If the hot and sour soup has been in the refrigerator longer than 5 days then it's likely spoiled or going to be spoiled and should be thrown out.
If you want to keep your hot and sour soup longer than a few days it's best to put the Hot and Sour Soup in a freezer safe container and freeze it.
When frozen the Hot and Sour Soup is good for at least 6 months but can last a year and sometimes longer.
However after 6 months to a year it loses it's freshness but it remains safe to eat as long as it's remained frozen.