Start by washing the russet potatoes thoroughly. Cut them into large chunks, about 1-2 inches each.
Place the eggs on a trivet inside the Instant Pot. Add 1 ½ cups of water to the bottom of the pot.
Add the cut potatoes to the Instant Pot, ensuring they are stacked on top of the trivet with the eggs.
Close the lid and set the valve to the sealing position. Select the manual or pressure cook setting and set the timer for 8 minutes.
Once the cooking time is complete, perform a quick release by carefully switching the valve to venting.
Transfer the eggs to a bowl of ice water to cool down quickly. Let the potatoes cool for a few minutes before draining any excess water.
In a large mixing bowl, combine the mayo, sour cream, mustard, salt, and pepper. Whisk together until smooth and creamy.
Peel the cooled eggs and chop them into small pieces. Add the chopped eggs and cooled potatoes to the dressing.
Gently fold everything together, ensuring the potatoes are coated without mashing them.
For the best flavor, refrigerate the potato salad for at least 30 minutes before serving.