Sautéing is cooking food in a small quantity of fat or oil. When sautéing, which is a type of frying, a very small amount of oil is placed in a shallow pan, and when it is sufficiently hot, the food is put into it. Foods that are to be sautéed are usually sliced thin or cut into small pieces, and they are sometimes turned frequently during the process of cooking. Sauter is French for "jumping", used to describe the action of the food in the pan.
The term pan-frying is sometimes the English equivalent of sautéing (which is a French word) if only a very small amount of oil is used. Some people consider it a different technique, which uses more fat and takes longer. Stir-frying uses higher temperatures and continual stirring. With modern non-stick pans the amount of oil required can be quite small, or even omitted.
Tips for Proper Technique
While different ingredients will call for variations in this technique, there are some general guidelines to help ensure an ideal outcome.
Mise en place
The first rule is be prepared. If your recipe calls for chopped ingredients in step 12, make sure you have them chopped now. While experienced cooks will successfully chop the next ingredient while the rest are cooking, this is not a path to follow for the inexperienced. For one thing, chopping times for the experienced cook are generally much shorter, so the cooking food doesn't have a chance to burn. For another, the experienced cook can quickly assess whether food is done. A less experienced cook should be much more attentive to the pan to become more familiar with the stages of "doneness".
The pan is hot enough if a few small drops of water flicked from your fingertips vaporise immediately, or if a larger drop of water hisses and floats across the surface of the pan on a cushion of its own steam.
Use the fond
When sautéing cuts of meat, many recipes will call for you to deglaze the pan with a flavorful liquid (e.g. stock, wine, spirits, or even fruit juices). The dark brown bits of meat left behind from the high heat cooking are called "fond" and are as intensely flavored as pan drippings from roasted meats. These should generally be scraped off the bottom of the pan and dissolved into the deglazing liquid. In especially elegant preparations, the pan sauce created is strained to remove the solid bits, leaving only the dissolved flavorings in a smooth sauce.
When using garlic and onion
When sautéing with both onions and garlic, be sure to sauté the onions first until they are clear, then add the garlic, and continue to sauté until it is pale gold. The onion takes longer to cook, thus if both are added at the same time, the garlic will be browned by the time the onion is done, which results in an undesirable dominant pungency. Garlic will add its flavour much more harmoniously when only sautéed to a pale gold.