Preheat the oven to 400°F. Place the boiled potato halves on a baking sheet. Drizzle with olive oil and season with salt. Toss well. Roast for about 25 minutes or until golden and crispy. Let the roasted potatoes cool for a few minutes.
Add the potatoes, onion, sun-dried tomatoes, Kalamata olives, roasted peppers, capers, parsley and basil to a large bowl. Gently mix everything together.
In a small bowl, whisk together the Dijon mustard, red wine vinegar, olive oil, salt, and black pepper.
Pour the dressing over the salad.
Gently mix everything together. Cover and refrigerate for at least 1 hour before serving.
Add a few basil leaves on top before serving, if you like.