Place a steamer basket in the liner of the pressure cooker and pour in 1 ½ cups of water. Add in the diced potatoes and place the eggs on top.
Put the lid on the pressure cooker and make sure the valve is in the closed position. Set to HIGH pressure for 4 minutes. Once finished, release pressure immediately. Place the eggs in a bowl of ice water to cool.
Remove the potatoes from the pressure cooker and place in a large bowl. Splash the potatoes with the white vinegar, gently tossing to coat while the potatoes cool. Meanwhile peel the eggs and give them a coarse chop.
In a small bowl combine the mayo, greek yogurt and mustard. Whisk together and season with salt and pepper to taste.
Once the potatoes are cooled, add in the chopped eggs, purple onion, celery and parsley. Gently fold in the dressing and cover. Place in fridge for a few hours if time allows to let the flavors blend and deepen. Enjoy!
Store potato salad in fridge until ready to enjoy. Potato salad can be made up to 3 days in advance, making it great for meal planning!