Saltiness of the tender corned beef is balanced with the sweetness of cabbage and carrots, and starchiness of potatoes.
Turn on the Instant Pot to SAUTE. Add oil.
Mix dry rub ingredients in a bowl. Prepare brisket with dry brisket rub.
Sear brisket, fat side up, for 3 minutes untouched in pot. At this time, add garlic to oil.
Flip over and sear brisket an additional 3 minutes on the fat side untouched.
Fat side down, place brisket on trivet so it is not touching the bottom of the pot. Add onions, apple cider vinegar, beef broth, and bay leaves to the pot. Keep brisket from being submerged in the liquid.
Close Instant Pot lid and set vent to seal. Use MANUAL button, 70 minutes.
Once pot beeps, let it count up 20 minutes. At 20 minutes, vent pot and open.
Place brisket on plate and cover with foil to rest.
With the Instant Pot still hot from brisket au jus, place potatoes, carrots, and cabbage (in this order) into the pot. Use MANUAL button, 1 minute. Vent once done.
Slice corned beef and arrange vegetables around it. Douse with au jus from the pot.
Serve (they say with mustard).