Onion powder is manufactured from dehydrated onions and is an acceptable replacement in recipes that call for fresh onions, although it will not provide as intense a flavoring. When it comes in contact with moisture or humidity, however, onion powder will clump because it absorbs the liquid. This does not mean that the powder is unusable and should be replaced. Instead, uncaking the powder will allow you to use it to flavor your favorite dishes, sauces and marinades.
Pour the caked onion powder into a shallow bowl.
Break up the onion powder with a fork. Use a jabbing motion to gently break up the clumps until the dehydrated onion returns to a powder form.
Pour the onion powder back into its original container.
Add six to 10 grains of uncooked white rice to the container to help absorb any moisture that comes into contact with the powder, which will help reduce any future clumping.
Close the lid tightly and store the onion powder in a cool, dry place to prevent future caking.