Drizzle olive oil into the Instant Pot and activate the sauté function. Once the oil is hot and shimmering, place the beef stew meat inside, seasoning it with salt, pepper, and Italian seasoning. Sear the beef until it develops a rich brown crust on all sides. Pour in the beef broth, ensuring that any browned bits stuck to the base are loosened with a spoon. Stir in Worcestershire sauce, minced garlic, chopped onion, sliced carrots, cubed potatoes, and tomato sauce. Secure the lid and close the steam valve. Set to cook under high pressure for 35 minutes. Once cooking is complete, allow the pressure to release naturally for 10 minutes before performing a quick release. In a separate bowl, whisk together cornstarch and cold water until smooth, then incorporate this mixture into the stew, stirring until the broth thickens to the desired consistency.