Start by thoroughly washing the potatoes, no need to peel them. Cut them in big cubes. Place them in a large pot, cover with water, add sprinkle of salt and bring to a boil. Cook until they are tender when pierced with a fork, about 15 minutes. Drain and let them cool slightly.
While the potatoes are cooking, prepare your other ingredients. Slice both the onion and the red onion into thin strips.
Give the capers a light chop with a knife; you want them to be slightly broken down but not finely minced. Pit and roughly chop the Calamata olives. Also, chop the sun-dried tomatoes into smaller pieces.
Using scissors, snip the fresh basil leaves into small ribbons or pieces. This helps release their aroma and distributes them evenly.