Turn the electric pressure cooker to the Sauté function, add 2 Tablespoons of the oil and heat until shimmery.
Put half of the beef cubes into the cooker and cook, stirring occasionally, until browned. Remove the beef to a bowl and add the other pound of meat to the pot to brown. If you think you need to add a bit more oil, then add it 1 Tablespoon at a time. Sometimes I do and sometimes I don't.
When those cubes are browned leave them in the pot and add about ½ cup of the beef broth. Stir, scraping up the browned bits on the bottom. This gets all that delicious caramelization incorporated into the mixture.
Add the potatoes, carrots, and onion, then put the first batch of beef on top and add the rest of the broth, the Guinness, balsamic vinegar, thyme, bay leaf, salt and pepper.
With the side of a wide knife or mallet, smash the garlic cloves and throw them into the mixture. Then give it a stir to mix it all up.
Turn the Sauté function off and set the pot to pressure cook on HIGH for 25 minutes. It usually takes about 15 minutes to come to pressure, then 25 minutes to cook.
Once the 25 minutes is up, let the pressure release naturally for 15 minutes, then do a quick release.
Use a slotted spoon to move the meat and veggies from the pot to a serving bowl, remove the bay leaf and discard.
Now thicken the gravy. Turn the pot to the Sauté function then whisk in the 2 Tablespoons of corn starch until dissolved. Cook, whisking occasionally, until thickened. This should take about 5 to 8 minutes.
Pour the gravy over the beef mixture, sprinkle with chopped parsley, and serve.