Set a 6-qt Instant Pot® to the high saute setting.
Season beef with 1 1/2 teaspoons salt and 1 teaspoon black pepper. Heat oil; add beef and cook until evenly browned, about 2-3 minutes per side; set aside.
Add onion, and cook, stirring frequently, until translucent, about 2-3 minutes. Stir in garlic and tomato paste until fragrant, about 1 minute.
Stir in red wine, scraping any browned bits from the bottom of the pot.
Stir in beef stock, Worcestershire, thyme, rosemary, bay leaves, potatoes, carrots and mushrooms. Top with beef. Select manual setting; adjust pressure to high, and set time for 60 minutes. When finished cooking, quick-release pressure according to manufacturer’s directions.
Remove beef, potatoes and carrots from the Instant Pot®; shred beef, using two forks.
In a small bowl, whisk together cornstarch and 1/4 cup cold water; set aside.
Select high sauté setting. Bring to a boil; stir in cornstarch mixture and cook, stirring frequently, until slightly thickened, about 2-3 minutes. If the mixture is too thick, add more beef stock as needed until desired consistency is reached. If using mushrooms, sauce may be a bit thin, reduce before adding cornstarch slurry.
Serve beef, potatoes and carrots with juices immediately accompanied by rice or buttered noodles or a nice crusty bread to sop up the sauce.