In a small bowl, combine garlic powder, onion powder, Kosher salt, and ground black pepper. Rub the short ribs with the garlic powder mixture.
Set the Instant Pot to saute on High. Add the olive oil, when it reads hot, add the seasoned short ribs to brown. (see note 2) Once browned, remove ribs from the Instant Pot, set aside.
Keep the Instant Pot on Saute, add the onions, carrots, and garlic to the pot. Let saute about 5 minutes. Add in the Guinness Beer( see note 3). Use a wooden to release the brown bits that have stuck to the bottom of the pot. Hit "Cancel" on the Instant Pot (Note 4)
Add in the beef broth, Worcestershire Sauce, and tomato paste. Stir to blend the tomato paste into the liquid. Add the seared short rib back into the pot. Also add in the thyme, parsley, and rosemary. (Note 5)
Place the lid on the Instant Pot and Seal it. Turn the Vent Knob to closed. Press "Stew" and set for 35 minutes, on high.
Once the timer goes off, let it do a natural release for about 10 minutes. Then open the valve to release the remaining pressure in the pot. Hit "Cancel". Remove cover, remove the ribs and carrots to a large bowl and cover with foil.
Make a slurry with the cornstarch and some of the liquid and mix well, until smooth. Pour into the Instant Pot and press "Saute" adjust heat to medium heat. Let it cook for about 10 minutes to thicken the sauce.
Serve the short ribs over mashed cauliflower, mashed potatoes, or egg noodles and enjoy!