In its natural state, beef brisket is one of the toughest pieces of the steer. It's a flat, leathery cut made of unusually long and stringy muscle fibers. However, when it's cooked long and slow at a low temperature, brisket is utterly transformed. Its plentiful supply of connective collagen cooks away to gelatin, leaving the muscle soft and toothsome. It's common practice in many restaurants to prepare one or more whole briskets ahead of time, then store them overnight for slicing and use.
There are several ways to prepare brisket. If it's first cured by salting, it becomes corned beef. If it's smoked and spiced as well, it becomes pastrami. Both of these, and plain fresh brisket, can be cooked by simmering them until fork-tender in water with onions, garlic, cloves or other ingredients. In Texas, brisket is rubbed with a dry spice mixture and then slow-cooked over wood smoke. However the brisket is prepared, it should be cooled and stored in the same way.
Once the brisket is fully cooked and tender pieces can be removed easily with a fork, it must be cooled quickly to keep it food safe. The U.S. Department of Agriculture's Food Safety and Inspection Service requires all cooked foods to be packaged for refrigeration within two hours of cooking, and preferably as soon as they're cool enough to be handled. A whole brisket is a large cut, so for rapid cooling cut it into sections with a sharp knife. Cover each piece loosely with wax paper or aluminum foil, and refrigerate it immediately.
Once the pieces of brisket have cooled, they can be packaged for refrigeration overnight or as needed. If you have airtight plastic containers in the right size, you can use those to store the brisket. Wrap the brisket first in plastic wrap to provide further protection against drying out. If suitable containers aren't available, divide the brisket and place the pieces into heavy duty zipper-seal freezer bags. Label and date the bags or containers, in case the brisket is not all used up the next day. Check your refrigerator's temperature with a household thermometer to ensure that it's at 40 F or lower, for food safety.
Reheating the Brisket
The best method for reheating brisket, regardless of how it's prepared, is by steaming. The brisket can be reheated by the piece or after slicing, as needed. Reheating a large unsliced portion of brisket can take 20 to 30 minutes, depending on its size. Sliced brisket can take as little as two to three minutes. Either way, steaming leaves the meat warm and succulent without drying it out. If you are hand carving the brisket, it's usually easier to slice the meat cold and heat the slices.