Place corned beef in the slow cooker fat side up, sprinkle with the seasoning packet and add the water. Place the potatoes and carrots around the corned beef and cook on low for 8 hours or until tender. Add the cabbage wedges during the last 40 minutes of cooking time to avoid overcooking. If you prefer firmer vegetables, add the potatoes and carrots halfway through the cooking time.

Place the corned beef fat side up in the Instant Pot, then sprinkle with the seasoning packet and add the water. Secure the lid and cook at high pressure for 60-90 minutes or until tender. Quick release the pressure and remove the lid when it’s safe to do so. Remove all but 1 cup of liquid from the Instant Pot.

Place the potatoes and carrots around the corned beef, and place the cabbage wedges on top. Secure the lid once more and cook at high pressure for another 5 minutes, then quick release the pressure.