Q. What is a roux?

A. A roux is a thickening agent made from equal amounts of flour and fat that is commonly found in sauces, gravies, soups and Cajun and Creole cookery. You'll want to use a roux when you would like to add thickness and richness to your sauce or soup.

Q. How do I make a roux?

A. To make a basic roux, start by measuring, by weight, the amounts of fat and flour desired. It's a one-to-one ratio (e.g. 4 ounces of fat and 4 ounces of flour equal 8 ounces of roux). Butter is the most commonly used form of fat. Melt the butter over medium heat, being careful not to start browning it, then slowly add the flour to the butter, whisking constantly. Within 2 to 3 minutes the roux will have the consistency of cake frosting. Now you're ready to add your liquid. Be sure to add only cool liquids or ingredients to a hot roux, or hot liquids to cool roux. As you incorporate the liquid into your roux, be sure to whisk frequently and pour slowly. Once combined, heat the entire mixture until it comes to a simmer. This process will keep the roux from creating lumps. Once all of the liquid has been added to the roux, cook the sauce or soup for at least 20 minutes, otherwise your finished product may have a granular or gummy texture. For more detailed roux facts, give Roux the Day a read in our Cooking Basics section!

Q. Isn't there an easier way to thicken my soup?

A. There are many! The simplest is to cook it with the lid off - the water will evaporate, resulting in a thicker soup. You can also puree soups in batches in a food processor or using an immersion blender for added texture. Peruse The Plot Thickens for other inventive ways to thicken your soup.

Q. What's the best way to thin a soup?

A. It's as simple as adding liquid. A little more cream, a little more broth or water -- if your soup is too thick, gradually stir in more liquid until it reaches the perfect consistency.

Q. Is there really enough liquid in that slow cooker soup recipe?

A. Yes! Because slow cookers work at low heat and with their lids on, there is hardly any liquid lost during cooking. In fact, it may appear after 8 hours that you have even more liquid than when you started. That's because almost all food, especially meats and vegetables, contain water. As they cook, they begin to release their water. With most cooking methods, the water turns to steam and evaporates. But, since the lid is on the slow cooker, there's nowhere for the steam to go; it just collects on the lid and drips back into the food. So, if you're inventing your own slow cooker recipes or adapting your favorite stovetop and oven recipes for the slow cooker, decrease the amount of liquid you would normally use on the stovetop.

Q. Which soups are better the next day?

A. Nearly all soups, allowed to cool completely then stored in airtight containers in the refrigerator, are improved in flavor the next day. The exceptions are soups made with seafood, which tend to lose their flavor the second day.

Q. What's the best way to freeze soup?

A. The best way to freeze anything is to let it cool completely, then divide it up into portions that you might want to use later, and seal it in an airtight, moisture-proof container before putting it in the freezer. If you're making extra soup to freeze, stop cooking it just before the vegetables are tender. When you freeze, thaw, then reheat it, you can finish the cooking process. If your soup has raw eggs or particularly delicate vegetables in it, leave them out entirely before you freeze. Frozen, thawed and reheated very tender vegetables and eggs won't come out quite the same the second time around. Read Just Freeze It! for more hints about packaging and the longevity of frozen food.

Q. I often find myself adjusting recipes in order to make enough for my family, but it doesn't quite work for some recipes. Do you have any advice for me?

A. Changing recipes in order to make more or less servings is called "recipe scaling." Whenever you alter the amounts of ingredients for a given recipe, you may also need to adjust the cooking temperature, cooking time, pan size and seasonings. But for food chemistry reasons, recipe scaling simply does not work well for some dishes: delicate foods such as soufflés, baked items requiring yeast such as breads, and recipes for a single large item that is meant to be later divided into smaller portions such as cakes, pies, breads and whole turkey.