Add the water to the bottom of the instant pot. Then add the rack insert. If you don’t have the basket accessory for the Instant Pot, you can place the green beans into a small colander and place into the pot on top of the rack.
Close lid and turn vent to the closed position. Cook on high pressure for 1 minute. Do a quick release.
Remove colander of beans. Drain all excess liquid from the pot. Add beans into the empty pot and add the butter, garlic salt, and pepper. Stir to combine.
Store cooled leftovers in an air-tight container kept in the refrigerator for 4-5 days. I like to reheat my green beans in a skillet over medium-low heat to keep them fairly crisp, but you can also microwave them in 1-minute increments until warmed through.