Using cornstarch to thicken a soup or glaze a dish is a very common chinese cooking technique.
The representative soups using this technique is the hot and sour soup and westlake beef soup.
Ingredients are usually diced or shredded quite finely and parboiled. Look at the hot and sour soup, all the ingredients are sliced and julienned. Each spoonful contains so many different tastes and textures.
Soups should be lightly seasoned before thickening because it will be more difficult to season well after thickening.
How to prepare cornstarch solution
Cornstarch powder must not be added directly to the soups. The powder is very fine and tend to clump together. They will turn into a gooey blob when mixed with hot water.
To prevent lumps, always mix the cornstarch in some cold or room temperature water first. Place a few teaspoons of cornstarch powder into a small bowl. Add the same amount of water and mix very well. Cornstarch do not dissolve. What you will get is a milky mixture.
When making cornstarch solution, add water to the cornstarch instead of cornstarch to water. Cornstarch is very light and will float on the water making it difficult to mix.
The normal ratio of water to cornstarch is 1:1.5 but I prefer to make thicker cornstarch mixture because it means I need to add less to a pot of soup to thicken things up quickly.
How to add the cornstarch mixture to the soup
Cornstarch will settle if the mixture is left to stand for a while. Always give the mixture a good stir before added to the soup.
Pour the cornstarch mixture into the soup slowly, stirring to check the consistency. You want to achieve a nice smooth slightly thickened texture, not a sticky gruel or a starchy paste.
Stop adding the cornstarch mixture when the texture is achieved, add more if your preferred consistency is not met.
Be patient, do not pour everything in at one go. If you are new at this, for a start, add the cornstarch mixture one spoonful at a time. After adding, stir the soup well. Check the consistency, then add another spoonful.
There are other types of starchy powders that are good substitutes. These include potato starch and arrowroot powders.
Do you know that cornstarch can be used to make art paste? Cook a pot of cornstarch with water until it turns into a stiff starchy paste. Edible glue! I made a paper machie pig with it.
Grandma used to dunk my uncle's army uniform into cornstarch solution so that it would iron out straight and stiff.
Some thickened soup recipes
Firm tofu soup with carrot and bamboo shoot
A yummy thickened tofu soup recipe using firm tofu, ground pork, carrot and bamboo shoot
Silken tofu soup with dried scallop
A warm smooth silken tofu soup recipe with minced green leafy vegetable and dried scallop
A thickened fish soup recipe using bream fish and spinach.
