Things You'll Need
Salt and pepper
Herbs and spices
Shallow roasting pan
Tongs or spatula
The best way to prepare boneless pork sirloin depends on the cut. A roast is most manageable in the oven, while deboned chops or cutlets can be pan seared on the stove. In either case, allow the meat to come to room temperature before making it so it cooks evenly. An average roast needs about an hour or a little more on the kitchen counter -- just don't leave meat out at room temperature longer than two hours -- while 30 to 45 minutes is sufficient for chops or cutlets.
The Oven Method
Preheat the oven to 350 degrees Fahrenheit. Prep your sirloin roast while the oven heats up.
Season the roast with salt, pepper and other herbs and spices of choice. Use sea salt and fresh coarsely cracked black pepper to add texture and more pronounced flavors. Rosemary and thyme make nice additions. Pat the seasonings over the meat's surface.
Cover the bottom of a shallow roasting pan with a sheet of aluminum foil. Foil prevents the pork's dripping juices from cooking onto the bottom of your pan, greatly improving the dish washing experience after you eat.
Put the roasting pan rack in place and lay the sirloin roast on it. Set the roasting pan in the middle of the oven shelf. Cook it for about 25 minutes per pound -- boneless roasts take a little longer than bone-in cuts -- then check it for readiness with a meat thermometer. Pork is safely cooked when it reaches and holds 145 degrees F for 15 seconds at the center of its thickest part.
Rest the pork sirloin for about 10 minutes before cutting into it. If you don't let it rest, the juices released from the muscle fibers run out of the meat upon cutting, rather than absorb.
The Stovetop Method
Sprinkle salt, pepper and other desired herbs and spices onto a plate and mix them up well. Press both sides of the pork chops or cutlets onto the seasonings to coat.
Heat a large skillet on a burner set to medium-high heat for about three minutes. Add enough cooking oil for a liberal coating and toss in a pat or two of unsalted butter. Let the butter melt completely.
Place the pork cuts in the skillet and don't move it around, as the meat needs to remain in place to crisp and brown. Pan sear 1-inch-thick cuts for about three to four minutes, until the bottoms are golden browned; thinner cutlets need a little less time, while thicker chops may need another minute or so.
Turn the sirloin chops or cutlets with tongs or a spatula. Sear the second side for approximately the same amount of time as the first, until the bottom develops a similar golden brown color and the meat is firm, but not hard, to the touch. The meat should be white throughout. You can use a meat thermometer in thick chops to check readiness, but these tools aren't reliable for thin cuts of meat.
Rest the pork chops or sirloin cutlets for about 5 minutes before serving. As with a roast, this helps keep them juicy and tender; however, they don't need as much time because they're considerably thinner.
Don't transfer, turn or otherwise handle pork with a fork or anything that pokes holes in the meat. Pork juices escape during cooking through punctures, drying out and toughening the meat.