The tiny seeds of the sesame plant are an important source of cooking oil in Asia and elsewhere. For enthusiasts looking to cook Chinese food at home, buying a bottle of sesame oil is mandatory. However, there are two different kinds of sesame oil: the clear, or pure, kind; and the dark kind. For a novice, it's not always apparent which oil to use for which purpose.
Pure Sesame Oil
Pure sesame oil, the light golden variety, has a pleasant flavor. It's pressed from uncooked sesame seeds, and comes in both refined and unrefined versions. The unrefined versions are used in salad dressings and marinades, where their flavor can be enjoyed for its own sake. The refined version has a higher smoke point, and it's used as a cooking oil for meats and vegetables. It adds a mild sesame flavor and a subtle nuttiness to dishes.
Dark Sesame Oil
Dark sesame oil, as the name suggests, is much darker in color than the pale golden variety. It's pressed from toasted sesame seeds, which give it a coffee-like hue. The toasted seeds also give this oil a very intense sesame flavor, one that would be overpowering if it were used for cooking. Dark sesame oil is used instead as a condiment or flavoring, added to foods just before serving to give them a rich sesame flavor.
Both light and dark sesame oil are used to give flavor to a variety of dishes, in Western cookery as well as their Asian and Middle Eastern homelands. Light oil is better used in more delicately-flavored dishes, where its subtlety will not be overwhelmed by the other ingredients. Use light sesame oil in vinaigrettes, for example, with citrus juices or mild wine or rice vinegar. Dark sesame oil has a bold enough flavor to stand up to chilies, soy or stronger vinegars, making it suitable for intense dips and sauces.
Although most sesame oil is produced for culinary purposes, it has further uses. A 2002 paper from Purdue University identified several intriguing possibilities for further sesame research. Sesame oil contains a variety of potent antioxidants, thought to have potential for preventing cancer. It is also thought to reduce cholesterol, and has traditionally been used as a mild but effective laxative. It is also used in the preparation of some medications, and has potential for extensive use in the soap and cosmetic businesses.