Prepare the Roast - Cut the beef into a minimum of 2 pieces (3 to 4 pieces reccomended for better texture). Trim excess fat and dry the surface with a paper towel. Evenly season on all sides with about 1 teaspoon salt and ½ teaspoon black pepper.
Brown the Meat - Select "Saute" on the Instant Pot. Allow to heat, it will indicate "Hot" on the display when ready. Add olive oil to the pot. Once hot, add the beef and brown each side for 5 minutes. Sear each edge for 1 minute. Transfer to a clean plate.
Cook the Aromatics - Add onions to the pot, and saute until tender, scraping the bottom for any browned bits, about 2 minutes. Add garlic and thyme, and saute until fragrant, 30 seconds.
Make the Braising Liquid - Add tomato paste and flour to the pot, stir and cook for 1 minute. Add red wine and stir until the liquid is evaporated and a paste is formed, about 1 minute. Stir in balsamic vinegar and Worcestershire sauce. Slowly stir in the beef stock, scraping the bottom of the pot to deglaze the pan. Cook until the sauce thickens, about 2 minutes.
Add the Beef and Vegetables - Add the previously browned roast to the pot. Add carrots and potatoes on top of the beef.
Add Seasonings and Cover - Sprinkle ½ teaspoon of salt and ¼ teaspoon of pepper on top of the vegetables. Make sure the release valve is in the "Sealing" position. Place the lid on, turn and lock.
Pressure Cook the Meat - Press the "Manual" button on the Instant Pot on high pressure, and then set the timer to 65 minutes using the "+" or "-" buttons. It will take about 10 minutes for the pot to heat up and build pressure. You will see some steam release from the lid, and then the time will start on the display.
Release the Pressure - Once cooking time is complete, allow the pressure to naturally release for 15 minutes.
Open Lid - Use an oven mitt or towel to slowly and carefully twist the steam release handle on the lid to the "Venting" position. The initial release will spray some moisture around the pot so be careful. Remove the lid, opening the top away from you as steam will be released.
Rest the Meat - Transfer the roast to a cutting board, allow it to rest for at least 10 minutes. Spoon the carrots and potatoes on a serving platter or bowl, and cover to keep warm.
Strain the Cooking Liquid - Let the sauce sit for 10 minutes in the pot, then skim and discard the excess grease from the top. There should be about 2 ½ cups of sauce.
Reduce the Sauce - Select "Saute" on the Instant Pot. Once the sauce begins to simmer, allow it to reduce until slightly thickened or the desired consistency is reached, 5 to 8 minutes. There should be about 1 ¾ to 2 cups of sauce. Taste and season with more salt and pepper as needed.
To Serve - Slice the roast against the grain, or shred with a fork. Serve with vegetables, sauce, and parsley for garnish.
Notes
For Proper Braising: It’s important to have the meat submerged about halfway in the liquid. The liquid doubles in volume after pressure cooking, so only a small amount is added in the beginning.
If Beef's Texture is Still Tough: It most likely needs more time to cook under pressure. If the meat is not done but the vegetables are ready, transfer them to a separate bowl and continue to cook the beef.
To Reheat: The sliced beef and vegetables can be rewarmed in the thickened sauce.
MAKE IT GLUTEN-FREE: Cassava flour or Cornstarch can be substituted for all-purpose flour. If using cornstarch, dissolve 2 tablespoons in a ¼ cup of water. Add to defatted sauce and then stir and cook on the saute function until the liquid has thickened.