Cornstarch is the most common thickening agent in most of Chinese recipes because it is the easiest to handle, but potato flour, wheat starch, water chestnut flour or green bean flour can all be used and will give a smoother less sticky result. Make the thickening paste with any of these flours, using the same quantity as for cornstarch, but to avoid leaving a rubbery lump on the bottom of the wok mix the paste very thoroughly into the sauce at the temperature well below boiling point before bringing to the boil to thicken, or dissolve it first in the same amount of cold water before adding it into the sauce. About 75 ml (5 tbsp) to 100ml (6 tbsp) of liquid thickened with 10 ml (2 tsp) cornstarch or other flour gives the right amount of sauce for a braise containing 150 g (5 oz) meat.
Be aware that in British recipes the term "corn flour" means cornstarch, and the two cannot be substituted for each other. What is known as corn flour in the United States cannot be substituted for cornstarch.