Pork loin comes from the upper back of the pig, between the shoulder and the leg joint. Sold bone-in or deboned, loin roast can be very lean or can have some marbling, namely on the end closer to the ribs. As a large cut of meat, pork loin is more commonly cut into smaller portions and sold as 3- to 4-pound roasts, to be baked in the oven. To keep the meat juicy and moist, brine or season it before cooking, and check the internal temperature with a food thermometer to avoid overcooking the meat.
Parts and Seasoning
Boneless pork loin roasts are sold either as a rib end, also known as the top loin or New York pork roast, or as a center cut roast, also known as a sirloin pork roast. The center cut roast is leaner and doesn't have as much marbling, but many prefer it because it's evenly shaped, making it easier to cook. Both cuts of pork loin benefit from being seasoned before cooking. Soak the pork loin in a spiced brine for 24 hours in the fridge prior to cooking or, for something faster, rub it with dried spices, such as cayenne, cumin, chili powder, garlic powder, thyme and salt and let it sit for at least 20 minutes to 8 hours.
The Basic Roast
For a basic center cut roast, preheat the oven to 350 degrees Fahrenheit and place the pork roast in a roasting tray. Arrange cut root vegetables around the roast if so desired, and place the tray on a center rack in the oven. Pour in 1 cup of stock, wine or water and apple cider into the roasting tray and cook, uncovered for 45 minutes. Check the roast every 5 minutes, spooning cooking liquid over it to baste if you wish. Cook the roast for another 45 minutes, bringing the oven temperature up to 375 F and continue to baste every 10 minutes. When the pork is done, remove it from the oven and let it rest, tented with foil, for 15 minutes before slicing and serving.
Pork loin can be seared and roasted at a lower temperature to increase the flavor and create a crispier crust on the exterior of the roast. Seared and roasted pork loin is best made with the rib end of a pork loin roast, as the extra marbling keeps it moist and tender during the slow cooking.
Preheat the oven to 200 F, and heat a large, oven-safe, heavy-bottomed skillet, such as a cast iron pan, on the stove. The pan needs to be large enough to comfortably hold the pork roast as well as any other vegetables you wish to cook with it. Pour in a thin layer of vegetable oil and heat on high heat until it is shimmering and just beginning to smoke. Place the roast in the pan, patting it dry first, and leave it untouched for 2 to 3 minutes, before turning it onto the other side. Sear all sides of the loin, except for the cut ends, for 2 to 3 minutes each, creating a dark brown crust. Transfer the loin, adding in any vegetables, and the pan to a center rack in the oven, pouring in 2-cups of liquid -- stock, wine or water all work. Cook for 40 minutes per pound, roughly 2 hours and 40 minutes, basting the pork roast every 20 minutes. Let the roast rest for 15 minutes after cooking, outside of the oven, before serving.
Food Safety and Doneness
All pork loin roasts are fully cooked and safe to eat when the internal temperature reads 145 F. While the meat firms up and turns white and the juices run clear when the pork is done, these are not reliable indicators. At 145 F, the center of the roast may still be slightly pink, but it is safe to eat. Pork roasts, as large cuts, will continue cooking after they have been removed from the oven, rising upwards of 10 degrees more during resting. To avoid overcooked, dried pork, test the internal temperature every 5 minutes during the last 40 minutes of cooking, and remove the roast from the oven when it reaches 130 to 135 F.