Pork butt, often called pork shoulder, is a cut of meat situated above the front shoulder -- commonly referred to as the picnic shoulder -- and between the atlas joint and the blade portion of the tenderloin. As with all cuts of meat, the more an animal utilizes a muscle, the "tougher" it becomes upon cooking, due to high concentrations of collagen, elastin and muscle density. However, when a highly used muscle, such as a beef rump roast or pork shoulder, is cooked using a low-heat, extended-duration cooking method -- five to six hours, depending on the type of oven -- the connective tissue dissolves, resulting in a tender final product.
Preheat the oven to 425 degrees Fahrenheit. Rinse the pork shoulder, then place it skin-side up on a cutting board and pat it dry with paper towels. Removing excess moisture from the pork helps facilitate a complex chemical process called the "Maillard" reaction, which -- upon the application of heat -- causes amino acids to undergo change on a cellular level that converts them to a form of carbohydrate that caramelizes. This conversion produces a browning effect on the surface of the meat, and contributes to overall quality in taste, texture and mouth feel.
Cut carrots, onions and celery into uniform pieces approximately 1 to 1.5 inches in size. Score or crosshatch the skin with a sharp utility knife, leaving a 1/2 inch of space between markings. Season liberally all over with kosher salt and fresh ground black pepper, making sure to incorporate seasoning into the scoring or crosshatching.
Place pork in the roasting tray and put it in the oven for approximately 30 minutes, or until the outside reaches a golden-brown color. Remove it. Add vegetables, bay leaves, braising liquid and garlic to the roasting pan. Cover with aluminum foil, allowing enough room inside for adequate air circulation, then seal it tightly. Reduce heat to 325 degrees Fahrenheit and put the pork back in the oven. Cook the roast for approximately six hours, or until the temperature reaches 160 degrees Fahrenheit in the center of the cut.
Remove the roasting pan from oven, place the pork on a clean cutting board and allow the meat to rest for approximately 15 to 20 minutes. Resting the meat allows the jus -- the meat's naturally occurring juices released during cooking -- to reincorporate back into the pork shoulder, resulting in a moist final product.