Braising is a form of moist-heat cooking in which the item to be cooked is partially covered with liquid and then simmered slowly at a low temperature.
Though it can be done on the stovetop, braising is best done in the oven, because the heat fully surrounds the pot and causes the food to cook more evenly than if it were only heated from below.
Begin by Searing
Because moist heat does not permit the various browning reactions that dry heat produces, giving cooked meats the brown, outer crust that also helps to develop complex flavors and aromas, it's customary to sear meat in a pan with a small amount of hot fat before braising it. This step helps to develop flavors as well as making the meat more appealing visually. Read more about how to braise meat.
How Braising Works
Braising is a good choice of cooking method for cuts of meat that are tougher or from older animals. The connective tissues that are more prevalent in cuts like this, and which can make meats tough and chewy when improperly cooked, are slowly dissolved through long, slow application of moist heat. So you end up with a tender piece of meat.
What's more, braising causes the muscle fibers to absorb moisture from the cooking liquid and steam. That gives you a juicy piece of meat. Finally, as the connective tissues break down, they dissolve and form gelatin, which thickens the cooking liquid and gives it body and shine. Meanwhile, the flavors imparted from the stock and vegetables, as well as any herbs and seasonings, are incorporated into the final product.
Low Temperatures, Slow Cooking
Braising involves cooking in a covered pot at temperatures of slightly more than 200°F. Cooking in the oven helps to maintain this steady temperature, so there is very little that needs to be done once the braising pot is transferred to the oven.
To achieve temperatures of 200°F to 210°F, the oven should be set to about 300°F. Because meat is a poor conductor of heat, moist heat that is transferred into the meat during cooking tends to remain in the meat, where it slowly breaks down the tough fibers in the meat.
Large cuts of meat can be braised, as with the so-called "pot roast." One thing to remember is that salting the meat before cooking can make browning it more difficult. So in order to season the meat properly, it may be preferable to season it through the cooking liquid itself rather than directly. Here's a classic beef pot roast recipe.
Braising is also a good way to cook tough, fibrous vegetables like celery, carrots, parsnips and so on. Vegetables to be braised would typically be sautéed, then covered with liquid and cooked in a covered pot in the oven.
With both meats and vegetables, the braising liquid can be reduced and thickened with a roux to create a sauce. it's important to skim the excess fat from the cooking liquid first, although some of the fat can be used for making the roux.