Boil the petite white or red potatoes in a large pot covered with cold water and a pinch of kosher salt. Bring to a boil, then simmer for about 15 minutes until fork-tender.

Prepare the dressing by combining extra-virgin olive oil, red wine vinegar, minced garlic, dry mustard, dried thyme, and dried oregano in a jar. Season with salt and pepper, and shake vigorously.

Drain the potatoes and let them cool for about 10 minutes. Cut them into halves or bite-sized pieces.

In a mixing bowl, combine the warm potato pieces with reserved caper brine. Add olives, sun-dried tomatoes, red onion, and dill. Pour the dressing over and toss gently.

Let the salad rest at room temperature for at least 1 hour. Just before serving, sprinkle crumbled feta on top.