How to Make It
In a medium saucepan, cover the potatoes with cold water and bring to a boil. Add a generous pinch of salt and simmer over moderate heat until the potatoes are tender, about 15 minutes. Drain and let cool slightly, then cut in half.
Bring a medium saucepan of water to a boil. Fill a large bowl with ice water. Add the haricots verts and a generous pinch of salt to the saucepan and blanch until crisp-tender, about 2 minutes. Drain and transfer to the ice bath to cool. Drain the beans again and dry thoroughly.
In a large bowl, whisk the olive oil with the vinegar. Add the potatoes, beans, tomatoes, olives, red onion and capers and toss gently. Fold in the basil and parsley, season with salt and pepper and serve.