Add Potatoes & Eggs To Pot: Add the water to the Instant Pot and then lower a mesh steamer basket with the cubed potatoes into the pot. Then place the eggs on top of the potatoes.
4-Minute Cook Time: Close the Instant Pot and set the pressure release valve to 'Sealing' and then set the pot to cook on 'Manual' / 'Pressure Cook', 'High Pressure' for 4 minutes.
Prepare Dressing: While the potatoes and eggs cook, add the mayo, mustard, Worcestershire sauce, finely chopped onions, salt, and pepper to a large mixing bowl and mix until combined into a smooth and creamy dressing. Set aside.
Quick Pressure Release: Once the cooking time has completed, perform a Quick Pressure Release by switching the pressure release valve from 'Sealing' to 'Venting'. Once the pin has dropped, open your pot.
Let Potatoes & Eggs Cool: Remove the potatoes and eggs from the pot. Place the eggs in a bowl of ice water and the basket of potatoes on the counter. Allow the potatoes to cool fully, about 30 to 45 minutes, before mixing them with the dressing.
Peel & Chop Eggs: Peel the eggs once they have cooled. Slice one egg to use for topping the potato salad and chop the remaining eggs for mixing into the salad.
Combine Potatoes, Eggs, and Dressing: Once the potatoes have cooled, move them to a large mixing bowl and toss with the vegetable oil. Now add the chopped eggs and dressing to the mixing bowl and mix until fully combined with the potatoes.
Serve and Enjoy: You can now transfer the potato salad to a serving bowl and top it with the sliced egg. Enjoy!