Step 1

Add the sliced onion and 3 cups water to the pressure cooker insert. Cut the Corned Beef in half and place it on top of the onions. Seal the lid and make sure the valve is in the “sealing” position. Cook for 70 minutes on Manual/High. (Note: That cooking time is for a 3-pound Corned Beef, if you're cooking a half portion, reduce the cooking time to 50 minutes.)

Step 2

Once the pressure cooker beeps and the time is up, manually release the steam. To do that, I place a kitchen towel on top of the valve and carefully turn the valve with tongs, being careful of the steam that releases. When the pressure has released, the pin on the lid of the pressure cooker will pop up and you can easily turn and open the lid.

Step 3

Add the potatoes, cabbage and carrots and reseal the lid. Make sure the valve is set to “sealing.” Set the time to 10 minutes on Manual/High.

Step 4

Once finished cooking, manually release the pressure by rotating the valve with tongs to carefully release the steam. Open the lid and check the internal temperature of the Corned Beef, it should be at least 160 degrees F measured on an instant read meat thermometer.

Step 5

In your slow cooker insert, add the sliced onion and 4 cups water. If the Corned Beef doesn’t fit in one flat layer, cut it into two pieces so it will lay flat in the slow cooker. Place the beef on top of the onions along with the pickling spices. Add the slow cooker lid and set to HIGH for 5 hours or LOW for 8 hours. After 2 hours of cooking time, add the cabbage, potatoes and carrots. Replace the lid and continue to cook the Corned Beef and vegetables until fork-tender and the internal temperature reaches at least 160 degrees F.

Step 6

In a large Dutch oven or large soup pot, add the sliced onion and the Corned Beef. Add enough water to cover the Corned Beef by an inch, about 6 cups.

Step 7

Bring the onion, water and beef to a simmer, then cover and keep the heat on low. Keep simmering the meat in the liquid, covered, until fork tender, about 3-4 hours. The internal temperature of the meat should reach 160 degrees F.

Step 8

Remove the meat from the pot and place on a large plate or platter; cover with foil. Transfer the meat to a pre-heated 200-degree oven to stay warm.

Step 9

Add the vegetables to the pot. If there isn’t enough liquid because some of it has evaporated during the cooking process, add another 1-2 cups of water, or enough to come up to the top of the vegetables. Raise the heat to medium and cook the vegetables, covered, until fork tender. About 25-30 minutes.

Step 10

The last 5-10 minutes of cooking the vegetables, add the meat and any accumulated juices back to the pot. Stir to combine.