Start by washing your firm Yukon Gold potatoes well. Peel the skins off if you prefer a smoother salad. Cut the potatoes into one-inch even square cubes. Place them into your large pot with cold water.

Add a large pinch of salt to the water. Bring the pot to a boil over high heat. Simmer the potatoes for about ten to twelve minutes. They should be tender when poked with a fork.

Pour the potatoes into a colander in the sink. Let the steam escape for at least five minutes. Spread them on a tray to cool down faster. This prevents the mayo from melting later on.

Grab your small bowl for the creamy salad base. Whisk together the mayo, mustard, and the cider vinegar. Add the salt and black pepper to the liquid. Stir until the dressing looks very smooth and thick.

Dice your crunchy celery and your sharp red onion. Chop the hard-boiled eggs into small chunky pieces as well. Finely chop the fresh parsley for a green garnish. Add these to the cooled potatoes in the bowl.

Pour the creamy dressing over the potato mixture slowly. Use a large spoon to fold everything together gently. Be careful not to mash the soft potato cubes. Every piece should be coated in the white sauce.

Cover the bowl with plastic wrap or a lid. Place it in the fridge for two full hours. Chilling helps the flavors soak into the starchy potatoes. Serve it cold at your next outdoor lunch.