Set to "sear" and pour water into pressure cooker. Add brisket.
Bring water up to a rolling boil.
Skim residue from surface.
Add garlic and bay leaves.
Close lid and lock. Set to "meat/stew" and adjust for 1 hour, 15 minutes.
When done, quick release until all pressure is released.
Open and add vegetables to brisket and cooking liquid, stirring gently.
Close lid and lock. Set to "potatoes" for 6 minutes.
When done, quick release until all pressure is released.
Open. Remove corned beef and transfer to a platter or cutting board. Cover loosely with foil. Let rest for 5 minutes.
Slice across the grain. Serve with horseradish sauce (optional).