Start With a Roux

• Create a roux. A roux is a mixture of equal parts flour and fat -- usually butter -- cooked together before other ingredients are added. It's often used as the base for French-style sauces but it also works as a soup thickener. Melt the butter but do not let it darken. Add the flour a little at a time, constantly whisking to avoid lumps. Use a low to medium flame to avoid scorching. For soups, you only need to cook a roux for a few minutes -- until the raw taste of flour is gone. The biggest disadvantage of this method is you have to predict beforehand that you'll need it, as it's meant to be the first step of a soup recipe.

Mash Some Beans

• If you find you need to thicken your soup near the end of the cooking time, mash or puree some of the beans. Use a potato masher to mash the beans in the pot, or remove some of the beans and broth to a blender or food processor. The mashed beans add body to the soup. The only disadvantage of this method is that now your soup is a bit less chunky than it was before.

Use a Slurry

• A slurry is a mixture of starch and liquid you add to a soup at the end of the cooking process. It's a good quick fix for a broth that's flavorful but a bit thin; it's also a fat-free fix. You can use flour, cornstarch, arrowroot or potato starch as a thickening agent; whisk up to 4 tablespoons with a cup of hot broth and add it to the pot. You can use a slurry in conjunction with a roux but in that case, choose a starch for the slurry other than flour.

Try Some Beurre Manie

• Beurre manie means "kneaded butter" in French and that's exactly what it is: A mixture of equal parts flour and butter kneaded together to form a paste. Add pinches of beurre manie to the soup as a very last-minute thickener. This is a good method to use if you like using flour-butter thickening agents but did not begin your soup recipe with a roux.