Turn the Instant Pot on to “Saute” setting. Add the grapeseed oil and the stew beef.
Sprinkle the Montreal Steak Seasoning on top of the beef. Mix well and cook for 5 minutes until most pieces of beef are browned.
Pour ¼ cup of the beef broth in the Instant Pot to “deglaze” the bottom of the pot.
Then, add in the potatoes, carrots, celery, onions, and garlic. Cook for 5 minutes.
Turn off the Instant Pot and add the parsley, green beans, the diced tomatoes, frozen green peas, green corn, mushrooms, and the remaining beef broth. Give the soup a stir.
Place the lid on the Instant Pot making sure the valve is set to “seal”. Press the "soup" setting. Set for 15 minutes*. Once done cooking, and the timer beeps. Let the soup do a natural rest for 40 minutes until the pressure pin drops. Carefully, remove the lid and give the soup a stir.
Season with salt and pepper and ladle into bowls.