Make oven-baked corned beef by trimming the corned beef brisket, rinsing it with water, and placing it in a roasting pan with the fatty side up. Cook the meat for three to four hours.
Prepare the corned beef brisket by first trimming the fatty layer, removing most of, but not all, of it. Rinse the meat with cool water, making sure to rub the flesh to activate the salt. To remove some of the salt, briefly immerse the corned beef in boiling water a few times before baking it. Place the meat in a large roasting pan, positioning the brisket so that the fat faces upward so that the fat bastes the rest of the meat as it cooks. Add 8 cups of boiling water to the pan or enough that there is between 1/4 and 1/2 inch of water.
You can further season the meat by adding lemon and onion slices to the top of the brisket or sprinkling it with peppercorns and cloves. Tent foil over the brisket or place the lid on the pan. Bake the corned beef at 325 degrees Fahrenheit for two hours. You can either turn the meat and continue cooking for another one to two hours until the brisket is done, or you can raise the oven rack and broil the meat for 30 minutes until the top turns crispy.