Corned beef and cabbage is a tradition in much of the country on St. Patrick's Day, and with the addition of extra vegetables it's the much-loved New England boiled dinner. Either way, simmering the corned beef to tenderness ordinarily takes hours. With a pressure cooker that time can be reduced to just over one hour, and your house won't be filled with strong-smelling steam.
Check the seal on your pressure cooker for any cracks, bulging or other irregularities that might prevent it from sealing your cooker tightly. Examine the vents and pressure gauge closely, to ensure they're free of debris and operating smoothly. Set the lid aside.
Unwrap the corned beef and rinse it well under cold running water. Trim away the surface fat with a sharp knife, leaving just a thin layer to help the corned beef hold together after it's cooked.
Place the rack in your pressure cooker. Transfer the beef to the pressure cooker, and add spices, chopped onion or other flavoring ingredients as desired. Pour 2 cups of fresh, cold water into the pressure cooker, and lock the lid in place.
Bring your cooker to a boil. When steam is escaping freely from the vent, close the valve and wait while the cooker pressurizes. When the pressure gauge shows 15 psi, reduce the heat. Keep your burner at the lowest temperature that will maintain the cooking pressure.
Cook the corned beef at 15 psi for one hour, then remove your pressure cooker from the heat. Let it rest for several minutes until the pressure releases on its own, then open the lid and insert a fork into the corned beef. If the meat is fully cooked, you'll be able to twist away a mouthful of corned beef. If not, return the cooker to the stovetop, repressurize it and cook for 10 more minutes at 15 psi. Again, let the pressure release on its own.
Remove the corned beef from the pressure cooker to a serving platter. Cover it loosely with foil and let it rest while you prepare the cabbage.
Peel the coarse outside leaves from a cabbage, and cut it vertically into six or eight wedges. Trim away most of the tough core from each wedge, leaving enough intact to hold the wedges together when they're cooked.
Remove all but one cup of the cooking water from the pressure cooker, and stack the cabbage wedges onto the rack. Lock the lid in place and bring the pot back to 15 psi pressure, as you did before. From the time the pot reaches pressure, cook the cabbage for four minutes.
Remove the pressure cooker from your stove to the kitchen sink. Run cold water over the lid until the pressure releases, taking care not to let it reach the valve or pressure gauge. Once the pressure has released, remove the lid and lift out the cabbage with tongs or a spoon. Serve the cabbage and sliced meat with boiled potatoes or other side dishes, as desired.