Peel and wash the potatoes, then cut them into bite-sized pieces that are 1 inch (2.50 cm) thick, add the cut potatoes into a stock pot, fill with cold water to 1 inch above the potatoes, season generously with sea salt and heat with a high heat
Meanwhile, finely chop the onion, finely chop the fresh parsley and add the olive oil & sherry vinegar into a bowl, whisk until well mixed
After 15 to 20 minutes and the potatoes are just cooked through, you can always pierce them with a toothpick, drain them into a colander, let the potatoes sit so the water can drain
Once the potatoes are cool enough to handle, add them back into the stock pot, along with the chopped onions, parsley and olive oil & vinegar dressing, season with sea salt & black pepper and gently toss together until well mixed
Transfer into a serving dish, serve chilled or at room temperature, enjoy!