Boil Potatoes: Place potatoes in a pot with cold water and kosher salt. Bring to a boil, then simmer for 15 minutes until fork-tender.

Prepare Dressing: In a jar, combine olive oil, red wine vinegar, garlic, dry mustard, thyme, oregano, salt and pepper. Shake well.

Cool and Cut Potatoes: Drain potatoes, cool slightly, then cut into bite-sized pieces. Drizzle with caper brine.

Assemble Salad: In a bowl, combine potatoes, olives, sun-dried tomatoes, capers, onion, and dill. Add dressing and toss.

Add Feta: Crumble feta over salad and gently fold in.

Rest Before Serving: Cover and refrigerate for at least one hour before serving.