1. Pour beef broth into stainless steel Instant Pot insert. Add quartered white onion and smashed garlic gloves.
2. Rinse corned beef off to clear excess salt.
3. Spice meat with provided spice packet and place corned beef into Instant Pot. It should be nearly covered by the beef broth. Set Instant Pot to manual high pressure for 60 minutes. When the timer sounds, allow pressure to release naturally (or use natural release for 10 minutes and then carefully select quick release).
4. When the pressure valve drops, open Instant Pot and add potatoes and carrots. Lock lid back in palace and set the timer for six minutes. When the timer sounds use the quick release setting to release additional pressure.
5. Add quarters or lightly shredded cabbage to the pot, lock the lids and allow to steam until you're ready to plate and serve.