Setup the Instant Pot by placing the steamer basket in the bottom of the cooking container.
Add the desired about of potatoes to the steamer basket inside the pot.
Next add 2 cups of water to the Instant Pot.
Set the Instant Pot to pressure cook for 20 minutes.
Once cooked, release the steam from the Instant Pot. Remove the instant lid and allow to sit for a few minutes to cool down.
Remove the cooking container from the Instant Pot. Remove the steamer basket holding the potatoes from the pot. Do this with caution as it may still be very hot.
Remove the potatoes from the steam basket and place the potatoes back in the Instant Pot container or a bowl for mashing.
Using the potato masher, mash the potatoes until no large clumps remain.
Add the plant milk slowly to create the desired consistency. As the potatoes sit, they will soak up more of the liquid.
Add the salt and pepper, if desired.
Enjoy!