Place the potatoes in a large pot, cover with cold water, and add kosher salt. Boil and then simmer for about 15 minutes until tender. Drain and cool slightly.

In a jar, combine olive oil, red wine vinegar, garlic, dry mustard, thyme, oregano, salt, and black pepper. Shake until emulsified.

Let the potatoes cool until manageable, about 10-15 minutes. Cut into halves or bite-sized pieces.

In a mixing bowl, drizzle caper brine over warm potatoes, add olives, sun-dried tomatoes, capers, red onion, and dill. Fold gently.

Pour the dressing over the potato mixture and toss until coated. Adjust seasoning with salt and pepper. Top with crumbled feta.

Let the salad sit in the refrigerator for at least one hour before serving.