Chop up the onion, carrots, cabbage, and potatoes.
Set the Instant Pot to Saute.
Add one tablespoon of olive oil to the Instant Pot and saute the Corned Beef for 3 minutes on each side.
Add the rack and pour in the beer and one cup of beef stock. Put the corned beef on the rack and top with onions,seasoning packet and brown sugar. Set to Instant pot to "MEAT" and cook for 75 minutes. Quick release
Top with potatoes and carrots and cabbage. Cook for another 15 minutes using MANUAL. Slow release. If the veggies aren't quite soft enough for your family. Simply add another 10 minutes using MANUAL. Serve and enjoy!