Velveting the Beef:

1. In a large bowl, mix 2-3 tablespoons of cornstarch with 2 tablespoons of Worcestershire sauce to create a marinade. Add the beef cubes to the bowl and toss until they are evenly coated. Let them marinate for at least 15 minutes.

Searing and Sautéing:

2. Heat a large pan over medium-high heat and add olive oil. Once hot, add the beef cubes in batches, searing them until browned on all sides. Transfer the seared beef to the Instant Pot.
3. In the same pan, add a bit more oil if needed, then add the onions, carrots, and celery. Sauté until they start to soften and brown slightly, about 5 minutes.
4. Add the garlic and cook for another minute until fragrant. Stir in the tomato paste and cook for another minute.
5. Pour in the Guinness beer to deglaze the pan, scraping up any browned bits from the bottom. Allow it to simmer for a minute or two.

Instant Pot Cooking:

6. Transfer the vegetable and Guinness mixture to the Instant Pot with the beef. Add the beef broth, dried thyme, and bay leaves. Season with salt and pepper to taste.
7. Stir well to combine all the ingredients. Close the lid of the Instant Pot, set the valve to “sealing,” and cook on high pressure for 45 minutes.
8. After cooking, allow the Instant Pot to release pressure naturally for 10 minutes, then manually release any remaining pressure.
9. Open the lid carefully, adjust seasoning if necessary, and remove the bay leaves.

To Serve:

10. Ladle the stew into bowls and garnish with chopped fresh parsley if desired. Serve hot with crusty bread or over mashed potatoes for a hearty meal.