Add everything except the butter into your pressure cooker and give it a stir. Close the lid and make sure your valve is in the sealing position. Then set to high pressure for 22 minutes. It will take about 15-20 minutes for the pot to reach pressure.
When the timer is complete, allow your pressure cooker to naturally release for 10 minutes. Then release the remaining pressure and open the lid once safe to do so.
Stir in the butter or margarine, if using and add some salt and pepper, to taste. Serve garnished with fresh parsley or Parmesan cheese, if desired.
You may use any variety of mixed vegetables you prefer. Make sure to add them to your pot frozen, and not thawed, in order to withstand the cooking time.Cook time includes the time needed for your Instant Pot to reach pressure.Leftovers keep refrigerated for 4-5 days.