Place the stainless steel pot in the Instant Pot and add 2 cups of water to the pot.
Cut the potatoes into large chunks. Place inside a large steamer basket for the Instant Pot. Carefully place the eggs on top of the potatoes and place the steamer basket inside the Instant Pot.
Lock the Instant Pot lid in place and close the pressure release valve. Press the “Pressure Cook” or “Manual” button until it’s on “Normal” and press the “Pressure Level” button until it’s on “High”. Then press the +/- buttons until it shows “00:06” for six minutes. The Instant Pot will say “On” while it comes up to pressure and then will begin to count down.
When the Instant Pot is done, quick release the pressure by opening the pressure release valve, staying clear of the steam. Press “Cancel” to turn off the Instant Pot.
Carefully remove the steamer basket from the Instant Pot. Remove the eggs with tongs and place in a small bowl of cold water. Pour the potatoes out onto a large baking tray to cool.
While the potatoes are cooling, dice the onion and pickles. Place in a large bowl and add the mayonnaise, mustard and salt to the bowl. Mix together.
When the eggs are cool enough to handle, peel and dice. Add to the large bowl.
Add the potatoes to the bowl when they’ve cooled to the touch and gently mix together so the potatoes are coated by the mayonnaise mixture. Refrigerate until ready to serve.