Flour Power

• Flour is the classic thickener for a creamy corn soup. Known to help stabilize dairy proteins, flour serves two key purposes in corn soup -- to thicken and to prevent milk curdling. To prevent curdling, you must add the flour before the dairy. After sauteing onions in oil, add the flour and mix it well before adding both stock and milk to finish the soup. This classic roux technique ensures that you have a presentable finished product with no curdled milk.

Cornstarch at the End

• Cornstarch is a suitable thickener for corn soup when it's added later in the cooking process. Mix one part cornstarch with four parts cold water until it is well incorporated and has no lumps. Add in about a cup of hot broth from your soup and mix well until it is smooth. Add this slurry back into your soup, then let the soup simmer a few more minutes before serving.

Reach for Arrowroot Starch

• Use arrowroot starch just as you would cornstarch to thicken soup. Find the neutral-flavored starch at health food stores or Asian food markets. Add one part arrowroot starch to four parts cold water and mix well. Incorporate one cup of hot liquid from your soup and mix it together until no lumps are present. Add the slurry back to your soup, simmer a few more minutes and serve.

Puree Instead

• Forego a thickening agent and puree corn soup instead. After simmering the broth with potatoes and onions, use a immersion blender or transfer the soup to a blender. Puree it until it is creamy. The potatoes act as a thickener in this preparation, rendering any additional ingredients unnecessary. Add the corn and other vegetables into the soup and continue to cook until the flavors blend and the corn is done cooking.