Begin by placing your whole, unpeeled Yukon gold or red potatoes in a large pot filled with salted water. Bring to a boil over medium-high heat, then reduce to a simmer. Cook until tender, about 20 minutes.

Carefully drain the potatoes in a colander and let them cool slightly. Once cool enough to handle, peel and cut into bite-sized cubes. Set aside in a large mixing bowl.

In the bowl, add thinly sliced red onion, chopped parsley, tangy pickles, black olives, capers, and sun-dried tomatoes. Gently fold together.

Drizzle olive oil and balsamic vinegar over the potato mixture. Sprinkle with salt, chili flakes, and sumac. Mix to combine.

Carefully toss the salad to combine everything without breaking the potato cubes.

Taste and adjust seasoning as needed. Let the salad sit for about 15 minutes before serving.