Take the chuck roast out of the fridge then sprinkle liberally with Kosher sea salt and freshly cracked black pepper. Allow it to come to room temp for 30 minutes.
Select the "Saute" function on the IP and allow it to heat up, then add the olive oil and heat for 30 seconds. Begin to sear the chuck roast...
Each side will take about 5 minutes, make sure that it takes on a lot of color (color=flavor)...
Don't forget to brown the sides too! Then remove to a plate and set aside.
Add the tomato paste, carrots, celery, onion, parsnips, garlic, Rosemary, and Bay leaves and saute for 5 minutes, stirring frequently. (You can add 1 lb red potatoes in this step if desired) we make mashed.
Toss in the mushrooms, stir and saute for 1 minute.
Pour in the red wine and beef stock, stir and cook for a another 5 minutes to reduce and concentrate the flavor.
Introduce the Chuck Roast back to the IP along with any juices that have accumulated on the plate. Cover and seal, being sure that the pressure release is in the closed position. Switch the IP to "Manual + High" and set the timer for 60-80 minutes (60-min 3lb / 80-min 5lb roast).
Let Instant Pot naturally release pressure for 20 minutes, then release remaining pressure fully. Uncover and remove the roast and allow it to rest for 5 minutes. Mix the cornstarch and water until dissolved and then pour into the IP and stir to thicken the Au Jus from the roast to make a gravy.
Trim and slice the roast and serve with mashed potatoes and green beans if desired.