While this method doesn't end up saving a lot of time, the outcome is some tender, juicy and flavorful corned beef, with perfect cabbage and potatoes.
Remove corned beef from packaging, rinse and pat dry.
Place corned beef in a pressure cooker, cover with beer or vinegar, peppercorn packet, and water.
Tie fresh rosemary and thyme with kitchen string and add to pot. Add garlic, onion, celery, and bay leaves to pot
Set cooker to saute for 30 minutes, then skim the foam from the top.
Lock the lid in place and set the valve to sealing/pressure position.
Set to soup/stew setting for 1 hour and let the cooker go to work
Release the pressure valve and allow all steam to escape before opening the lid.
Add potatoes to the pot. If they are bite size, put them in whole, otherwise cut them into half or quarters, into a large bite size.
Put the valve back into the pressure/sealed setting and set the cooker to soup/stew for 10 more minutes.
Release the steam again, and add the cabbage wedges directly into the liquid. Lock the lid back on.
Set the cooker to steam setting, and steam the cabbage for 3 minutes.
Remove the lid, carefully remove food from the liquid onto a serving platter. Slice the corned beef against the grain and serve with mustard.