Put potatoes, carrots, mushrooms, thyme, garlic, onion, 2½ cups of vegetable stock, Worcestershire and wine in an instant pot.
Close the lid and seal the valve.
Cooke on manual “high” pressure for 20 minutes.
Release the pressure naturally.
In a bowl mix cornstarch in ½ cup of vegetable stock and whisk well.
Add it to the roast mixture, cook for 2 minutes until the sauce thickens.
Garnish with fresh parsley and serve.