1. Season the beef roast with salt and ground black pepper to taste.
2. Turn the instant pot/pressure cooker to "saute". Add half the oil and allow it to get hot. Add the beef to the pot and sear for about 3-4 minutes per side, or until golden brown. Remove the beef from the pot and set aside.
3. Add the remaining oil into the instant pot (it should still be in "saute" mode), when the oil is hot, add the onions and celery and cook, stirring frequently for about 2 - 3 minutes or until the onions become translucent. Add the carrots and garlic and saute for about a minute. Add the tomato paste and cook for about 2 minutes, stirring frequently.
4. Stir in the red wine and with a wooden spoon or spatula scrape the bottom of the pot to remove some of the bits stuck at the bottom of the pot. (*see notes), 
5. Stir in the beef broth, bouillon, bay leaves, Worcestershire sauce and return the meat and any collected juices to the pot. Add the rosemary and thyme. Select cancel/warm.
6. Lock the lid into place and set the pressure valve to sealing. Select "manual", high pressure and set the time for 64 minutes. 
7. Once done, let the pressure release naturally for 20 minutes and then do a quick release. Open the lid.
8. Remove the roast to a plate or cutting board. Carefully remove the carrots (they are very tender). Cover the beef and carrots with aluminum foil to keep warm. Skim some of the fat from the top of the liquid, and remove the bay leaves and the herb stems.
9. If pressure cooking the potatoes, you can shred the beef while the potatoes cook. Otherwise, do it as soon as you take the meat and carrots off from the instant pot.

The Potatoes (skip to "Thickening the Gravy" if not cooking potatoes)

1. At this point, you are ready to cook the potatoes (optional). Cut the potatoes in half and place them inside the instant pot. There should be enough liquid from the roast. 
2. Lock the lid into place and set the pressure valve to sealing. Select "manual", high pressure and set the time for 8 minutes. When finished cooking, quick-release pressure according to manufacturer's directions. Open the lid and remove the potatoes.

Thickening the Gravy

1. In a small bowl, whisk together the cornstarch with 2 tablespoons of water to make a slurry. Set aside.
2. Turn the instant pot/pressure cooker to "saute". Bring the sauce to a boil and add the cornstarch mixture, stirring frequently until slightly thickened.  If the mixture gets too thick, add more beef broth as needed until desired consistency is reached.
3. Serve the beef pot roast, carrots and potatoes with the gravy immediately.
4. If you won't be serving immediately, return the shredded beef to the instant pot (I like to keep the meat covered by the gravy as much as possible to keep the meat juicy. Place the potatoes and carrots inside the pot as well (on one side) and keep on "warm" until ready to serve.