Common Cooking Problems
No cooking technique is completely foolproof. Here are solutions to the most common problems that can arise during stir-frying.
Food Sticking to the Wok
This is one of the most common problems in stir-frying. The usual culprit is a wok that hasn't been preheated. Never add hot oil to a cold wok — always heat the wok for at least 30 seconds before adding the oil. The wok should be nearly smoking, and you should be able to feel the heat when you place your hand two to three inches above the wok's bottom.
Burning the Aromatics
Flavoring oil with aromatics (such as garlic and ginger) is a well-known cooking technique, designed to prevent an oily flavor from being imparted to the food. When you're stir-frying, however, there is a danger that the garlic will burn, adding a bitter flavor to the dish. Following the basic steps for stir-frying and stir-frying quickly will take care of much of the problem.
If you're still having difficulties, instead of stir-frying the garlic and ginger for 10 seconds, try pressing down on the garlic and ginger with a spatula, forcing them to quickly release their flavor into the hot oil.
A Lumpy Cornstarch Mixture
Thickening a sauce with cornstarch is one of those techniques that seems like it should be simple but can go wrong very quickly if you don't follow the correct steps.
Never add the cornstarch directly to a sauce heating in the wok or skillet. The cornstarch will not combine properly with the hot liquid, and the sauce will be lumpy. Instead, prepare a cornstarch slurry by dissolving the cornstarch in a small amount of cold water. Pour the slurry into the heated sauce and stir until the sauce thickens. You can also add the cornstarch to the sauce before it is heated, whisking in the cornstarch to combine it with the other ingredients.
Keep in mind that no matter how thoroughly you stirred it, it takes only a few minutes for grains of cornstarch to separate out of the slurry and settle on the bottom of the bowl. Always remember to stir the cornstarch and water mixture before adding it to the sauce.