Peanut oil works well in stir-fries and for deep-frying because of its high smoke point. When cooking oil reaches a temperature hot enough to smoke, it develops unhealthy free radicals, an unpleasant odor and a burnt flavor. Toasted sesame oil has a very low smoke point. Add it at the very end of a cooking process to enjoy its flavor while still preparing a healthy dish. Unrefined sesame oil has a higher smoke point than toasted sesame oil, so it works for high-heat cooking.

The sesame oil typically used to flavor stir-fries and soups comes from toasted sesame seeds, which provide a rich, nutty flavor characteristic of Chinese, Japanese and Korean cuisines. Peanut oil typically sold in American supermarkets has a neutral flavor, allowing it to take a back seat and let other flavors such as soy sauce, ginger and sesame oil feature more prominently.

Stir-frying cooks ingredients quickly on high heat, usually in a wok or large saute pan. Ingredients are cut into small pieces to ensure rapid cooking. Each piece should be individually coated with peanut oil, so stir-frying typically uses more oil than techniques such as stewing and braising, which incorporate additional liquid and cook ingredients more slowly. Cooks who are skilled at stir-frying also use heat, timing and blanching to avoid using more oil than necessary.

Use peanut oil or unrefined sesame oil for deep-frying. Heat the oil to between 350 and 375 degrees Fahrenheit. Test the temperature with a candy thermometer or drop in a small cube of bread to test whether the oil is hot enough to sizzle. Do not use toasted sesame oil for deep-frying.

Toasted sesame oil adds flavor to soups such as hot and sour soup and Asian-style chicken soups. Water-based soup stocks do not reach temperatures hot enough to break down toasted sesame oil, but the oil still retains optimum flavor if you add it at the last minute. Use peanut oil or unrefined sesame oil to saute soup ingredients such as onion and garlic, or to sear meats before adding them to soup broth.