Season the meat with salt and pepper on both sides.
Preheat the pressure cooker (I used my Instant Pot - affiliate link), select saute on high. Add in the oil.
Once the pot is hot, brown the chuck roast, 3-4 minutes on each side. Transfer the meat onto a plate and cover with foil (or parchment paper) to keep warm.
Add in the onion, garlic, chicken stock, and thyme and give it a stir.
Put the meat back into the pot and secure the lid.
Select manual, make sure that the steam release handle is turned to sealing position, and cook at high pressure for 60 minutes.
When cooking is complete, use natural release for 10 minutes and then release the remaining steam.
Add in the potatoes, carrots, and parsnips. Be sure to submerge them in the cooking liquid.
Select manual and cook at high for 10 minutes.
When cooking is complete, use a natural release for 10 minutes and then release the remaining steam.
Don't have parsnips on hand? Use 2 more large carrots instead.
Can I cook a frozen pot roast in my pressure cooker? You sure can. Cooking a frozen roast in an Instant Pot is actually quite easy. Place the frozen roast in the pressure cooker with the trivet underneath, to allow the heat to penetrate the entire surface of the roast, and add an additional 20 minutes to the cooking time. Frozen to pull-apart tender in no time!
Two options for making gravy:
TO BLEND (preferred method): Remove the beef roast and vegetables from the pressure cooker and scrape off the excess fat from the remaining liquid in the Instant Pot. Then, simply use your immersion blender to blend the sauce together, creating an emulsified gravy.
TO STRAIN: Remove the beef roast and vegetables from the pressure cooker and scrape off the excess fat from the remaining liquid in the Instant Pot. Then, strain through a fine-mesh sieve into a saucepan over medium heat and simmer until reduced and slightly thickened, about 10-15 minutes.