Start by placing whole, unpeeled Yukon gold or red potatoes in a large pot of salted water. Bring it to a rolling boil over high heat, then reduce to medium and cook for about 20 minutes, or until the potatoes are fork-tender.

Once the potatoes are cooked, carefully drain them in a colander and let them cool for about 5-10 minutes. Peel the potatoes, cut them into bite-sized cubes, and set them aside.

In the bowl with the cut potatoes, add the diced red onion, chopped parsley, sliced pickles, pitted black olives, capers, and chopped sun-dried tomatoes. Gently fold the ingredients together until they're well combined.

In a separate bowl, whisk together olive oil, balsamic vinegar, and sumac. Add a pinch of salt and chili flakes.

Pour the dressing over the potato and vegetable mixture, gently toss the salad using a spatula, and adjust the seasoning.

Serve your sumac potato salad immediately or refrigerate it in an airtight container for up to 3-4 days.