Pat the chuck roast dry with paper towels and season generously with salt and pepper on all sides.

Select the Sauté function on your Instant Pot and add the vegetable oil. When the oil is hot and shimmering, add the seasoned roast and sear until deeply browned on all sides, about 3-4 minutes per side.

Remove the seared roast and set aside temporarily. Add the sliced onions to the pot and sauté until softened, about 2-3 minutes. Add the minced garlic and cook for another 30 seconds until fragrant.

Pour in the beef broth, using a wooden spoon to scrape up all the browned bits from the bottom of the pot.

Stir in the Worcestershire sauce and tomato paste until well combined with the broth.

Return the seared roast to the Instant Pot and add the dried rosemary, thyme, and bay leaves.

Arrange the halved potatoes, carrots, and celery pieces around the roast.

Secure the lid and set the pressure valve to the sealing position. Select Manual or Pressure Cook setting and set the timer for 60 minutes at high pressure.

When the cooking cycle completes, allow for a 15-minute natural pressure release before carefully turning the valve to venting to release any remaining pressure.

Remove the roast and vegetables to a serving platter and tent with foil to keep warm.

Optional: For a thicker gravy, select the Sauté function. In a small bowl, whisk together cornstarch and water to create a slurry. Stir the slurry into the liquid in the pot and cook, stirring frequently, until thickened to your desired consistency, about 2-3 minutes.

Remove the bay leaves, taste the gravy, and adjust seasonings if needed.

Slice or shred the pot roast and serve with the vegetables and gravy.