Searing (or pan searing) is a technique used in grilling, baking, braising, roasting, sautéing, etc., in which the surface of the food (usually meat: beef, poultry, pork, seafood) is cooked at high temperature until a browned crust forms. Similar techniques, browning and blackening, are typically used to sear all sides of a particular piece of meat, fish, poultry, etc. before finishing it in the oven. To obtain the desired brown or black crust, the meat surface must exceed 150 °C (300 °F), so searing requires the meat surface be free of water, which boils at around 100 °C (212 °F).
Although often said to "lock in the moisture" or "seal in the juices", searing has been demonstrated to result in a greater net loss of moisture versus cooking to the same internal temperature without first searing. Nonetheless, it remains an essential technique in cooking meat for several reasons:
- The browning creates desirable flavors through the Maillard reaction.
- The appearance of the food is usually improved with a well-browned crust.
- The contrast in taste and texture between the crust and the interior makes the food more interesting to the palate.
A common misnomer linked with searing meat is caramelization. Caramelization is a process that affects only sugars, or simple carbohydrates. The Maillard reaction, by contrast, involves reactions between amino acids and some sugars.
Typically in grilling, the food will be seared over very high heat and then moved to a lower-temperature area of the grill to finish cooking. In braising, the seared surface acts to flavor, color and otherwise enrich the liquid in which the food is being cooked.
In reverse searing, the order of cooking is inverted. First the item to be cooked, typically a steak, is cooked at low heat until the center reaches desired temperature; then the outside is cooked with high temperature to achieve the Maillard reaction. This technique is typically recommended for thicker pieces of meat, 1-1 1/2 inches or thicker, allowing for consistent internal cooking temperature with only the outer portion becoming seared.
In addition to having a more consistent method to achieving the desired temperature on a thicker piece of meat, the reverse sear method typically gives off a fancier, restaurant style taste to your food so long as it is seasoned properly. There are multiple ways to reverse sear, but according to Andrew Rhea of Binging with Babish the best way to cook a thick piece of protein is to reverse sear on a low temperature via the sous vide method followed by drying the protein then searing it on the highest heat your cast iron pan allows. This ensures maximum moisture and tenderness with very little juice loss and resting times prior to cooking the protein. The reverse sear technique is popular amongst the households of chefs and food connoisseurs alike. 
Sealing in the juices
The belief that searing meat "seals in the juices" is widespread and still often repeated. This theory was first put forth by Justus von Liebig, a German chemist and food scientist, around 1850. The notion was embraced by contemporary cooks and authors, including Auguste Escoffier. It is more typically cited in regard to larger cuts, especially steaks and chops, of non-poultry meats such as beef, pork, lamb and tuna.
Simple experimentation can test the theory, in which two similar cuts of meat are cooked, one of which is seared and the other is not. Each piece is then cooked normally in a preferred method (roasting, baking, grilling etc.) until each reaches exactly the same predetermined internal temperature. They are then weighed to see which lost more moisture. Such experiments were carried out as early as the 1930s: the seared roasts lost the same amount of moisture or more. Generally more liquid is lost, since searing exposes the meat to higher temperatures that destroy more cells, in turn releasing more liquid.
Moisture in liquid and vapor form continues to escape from a seared piece of meat. For this reason, searing is sometimes done at the end of the cooking process to gain the flavor benefits of the Maillard reaction, as well as the benefits of cooking for a greater duration with more moistness.
- McGee, Harold (2004). On Food and Cooking (Revised Edition). Scribner. ISBN 0-684-80001-2. Page 161, "The Searing Question".
- Pryles, Jess (May 3, 2015). "Cook the perfect medium rare steak with Reverse Sear". Jess Pryles. Retrieved June 26, 2019.
- "Reverse Sear, Grilling Temps, When To Cook Hot & Fast, When To Cook Low & Slow, And When To Do Both". BBQ & Grilling In Depth. February 22, 2015. Retrieved June 26, 2019.
- Kenji López-Alt, J. (March 7, 2017). "The Food Lab". Serious Eats. Retrieved June 26, 2019.
- "How To Reverse-Sear A Steak". Binging With Babish. Retrieved 2020-10-15.
- McGee, Harold (1990), The Curious Cook: More Kitchen Science and Lore, page 13, "The Searing Truth"