2tablespoonscornstarchplus 2 tablespoons water to create a slurry
Pat the roast dry and cut 6 1-inch deep slits in the top. Peel the garlic cloves and cut them in half. Stuff each slit with a half clove of garlic and a piece of cut rosemary spring. Season all over with the salt and black pepper. In the bottom of an Instant Pot or similar electric pressure cooker or multi-cooker, pour in the water, then add the beef, nestling the pieces in snuggly.
Arrange the potatoes on top of the beef. Mince the remaining garlic and scatter on top of the potatoes. Sprinkle the chopped rosemary all over the potatoes and beef. Then, sprinkle a pinch of salt on top of the potatoes.
Pour the tomato sauce and Worcestershire over the beef.
Cover and seal the Instant Pot. Cook on Manual/High Pressure for 60 minutes. It will take 10 to 15 minutes for the Instant Pot to come to pressure, then the countdown will begin. When the cook time has elapsed, allow the pressure to release naturally for 10 minutes, then quick release any remaining pressure.
Carefully open the lid and add the baby carrots on top.
Reseal the lid and cook on Manual/High Pressure for 5 minutes more. Let the pressure release naturally for 10 minutes (this natural release is KEY for a tender roast). Quick release any remaining pressure. With a slotted spoon, remove the meat and vegetables to a large platter or bowl, discarding any large pieces of fat.
Make sure the Instant Pot is off. In a small bowl, briskly whisk together the slurry of 2 tablespoons cornstarch and 2 tablespoons water until smoothly combined. While whisking the cooking juices in the Instant Pot, slowly pour in the slurry. Turn the pot to SAUTE, then cook, stirring frequently, until the juices have thickened into a thin gravy, about 3 to 5 minutes. Turn off the Instant Pot.
Add the beef and vegetables back to the pot and stir to warm through (the potatoes, veggies, and meat will all break down a little and be tender and delicious). Serve hot, ensuring each serving gets a little bit of everything.
*Grandma used a 6-ounce can of V-8 juice, which is sold in multipacks. If you are a regular V-8 juice drinker, feel free to swap it here; reduce the Worcestershire sauce to 2 tablespoons.
**If you add the baby carrots at the beginning, they will be fairly obliterated by the time the roast is done, which is why this recipe directs for you to add them at the end. Growing up, we ate our veggies fairly mushy, so if you don’t mind your carrots very soft (we're talking completely falling apart), you can add the baby carrots at the beginning for ease. Or use regular carrots, scrubbed and chopped into large (2-inch) chunks; these cook more slowly and can be added with the potatoes. Set your cook time to 60 minutes as directed, let release naturally for 10 minutes, then vent and proceed with the gravy.
TO STORE: Refrigerate pot roast in an airtight storage container for up to 4 days. Spoon the gravy into a separate storage container.
TO REHEAT: Rewarm leftovers in a baking dish in the oven at 350 degrees F or in the microwave, spooning gravy over the pot roast before reheating.
TO FREEZE: Freeze leftovers in an airtight freezer-safe storage container for up to 3 months, storing the pot roast and gravy in separate containers. Let thaw overnight in the refrigerator before reheating.