Place your Instant Pot on the counter. Pour the water into the pot and place a steamer basket into the Instant Pot.
Peel the skin of the potatoes with a vegetable peeler. Then using a cutting board and large sharp knife, cut the potatoes into roughly 1 inch pieces, making sure they’re about the same size so they cook evenly.
Place the cut potatoes into the steamer basket then nestle all 5 eggs on top of the potatoes.
Secure the top of the Instant Pot, locking it in place and setting the vent knob on top to the secure position.
Set the timer of the Instant Pot for 4 minutes. Take out a medium-size bowl and place a cup or two of ice cubes in it with some very cold water. This will be used as an ice bath for the eggs once they’re done cooking.
Next take out the food processor to mince the vegetables.
Prep the shallot by peeling off an extra outside layers and the celery by washing any dirt off and chopping off the white wide part on the bottom (between 1 and 2 inches) with the knife.
Chop the vegetables into medium-sized pieces with the large sharp knife on the cutting board. Put the pieces of both the shallot and celery into the food processor and pulse until both are finely minced. Pour them into a large bowl, using a spatula or wooden spoon to scrape out any pieces that stick to the inside of the food processor.
Measure out 1 cup of mayonnaise and scrape it into the bowl with the spatula or wooden spoon.
Measure the remaining ingredients (yellow mustard, apple cider vinegar, kosher salt, and ground black pepper) using measuring spoons and dump them into the bowl with the mayo and vegetables. Stir with a wooden spoon or spatula until well incorporated.
When the timer goes off on the Instant Pot, push the knob on top to do a quick pressure release.
Once the pressure is done being released, remove the lid and with a spoon scoop the eggs out of the Instant Pot and into the ice water bath. Let sit for at least 5 minutes to cool.
Using a hot pad or oven mitt, carefully remove the steamer basked with the cooked potatoes from the Instant Pot. Dump them into the bowl with the mayonnaise mixture.
Once the eggs have cooled, peel them, discarding the shells. With a small sharp knife, cut 4 of the eggs into small pieces. This can be done by slicing an egg lengthwise 3 or 4 times, then giving it a quarter-turn and slicing it again 3 or 4 times lengthwise (on the other side), and finally slicing it widthwise several times to create small pieces. Dump the cut eggs into the bowl with the potatoes.
Mix everything together with a spoon until the mayo mixture is evenly spread around. If some of the potato pieces are too big, just split them in two using the spoon.
Cut the remaining egg into 4 or 5 slices and place on top of the salad. Sprinkle a dash of paprika on top for garnish, and eat!